Number

2,521

2,521 is a prime, odd.

2,521 (two thousand five hundred twenty-one) is an odd 4-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in Roman numerals it is MMDXXI and in binary, 100111011001.

Arithmetic Number Centered Square Cube-Free Deficient Number Odious Number Pernicious Number Prime Pythagorean Prime Recamán's Sequence Squarefree Star Number

Interestingness

★ ★ ★ ★ ★

8 notable facts · grade A

2,509 2,510 2,511 2,512 2,513 2,514 2,515 2,516 2,517 2,518 2,519 2,520 2,521 2,522 2,523 2,524 2,525 2,526 2,527 2,528 2,529 2,530 2,531 2,532 2,533

less more

Properties

Parity: Odd
Digit count: 4
Digit sum: 10
Digit product: 20
Digital root: 1
Palindrome: No
Bit width: 12 bits
Reversed: 1,252
Recamán's sequence: a(869) = 2,521
Square (n²): 6,355,441
Cube (n³): 16,022,066,761
Divisor count: 2
σ(n) — sum of divisors: 2,522
φ(n) — Euler's totient: 2,520

Primality

2,521 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 2521

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 2,521)

1 × 2521

First multiples

2,521 · 5,042 (double) · 7,563 · 10,084 · 12,605 · 15,126 · 17,647 · 20,168 · 22,689 · 25,210

Sums & aliquot sequence

As a sum of two squares: 35² + 36²

As consecutive integers: 1,260 + 1,261

Continued fraction of √n

√2,521 = [50; (4, 1, 3, 2, 1, 1, 1, 1, 6, 12, 2, 2, 33, 14, 3, 5, 1, 19, 4, 7, 2, 10, 1, 2, …)]

Representations

In words: two thousand five hundred twenty-one
Ordinal: 2521st
Roman numeral: MMDXXI
Binary: 100111011001
Octal: 4731
Hexadecimal: 0x9D9
Base64: Cdk=
One's complement: 63,014 (16-bit)
Scientific notation: 2.521 × 10³
As a duration: 2,521 s = 42 minutes, 1 second

In other bases

ternary (3) 10110101

quaternary (4) 213121

quinary (5) 40041

senary (6) 15401

septenary (7) 10231

nonary (9) 3411

undecimal (11) 1992

duodecimal (12) 1561

tridecimal (13) 11bc

tetradecimal (14) cc1

pentadecimal (15) b31

Palindromic in base 16

As an angle

2,521° = 7 × 360° + 1°

1° ≈ 0.017 rad

Compass bearing: N (north)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒌋𒌋𒁹𒁹 𒁹
Egyptian hieroglyphic: 𓆼𓆼𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺
Greek (Milesian): ͵βφκαʹ
Mayan (base 20): 𝋦·𝋦·𝋡
Chinese: 二千五百二十一
Chinese (financial): 貳仟伍佰貳拾壹

In other modern scripts

Eastern Arabic ٢٥٢١ Devanagari २५२१ Bengali ২৫২১ Tamil ௨௫௨௧ Thai ๒๕๒๑ Tibetan ༢༥༢༡ Khmer ២៥២១ Lao ໒໕໒໑ Burmese ၂၅၂၁

Digit at this position in famous constants

π — Pi (π): Digit 2,521 = 6
e — Euler's number (e): Digit 2,521 = 7
φ — Golden ratio (φ): Digit 2,521 = 6
√2 — Pythagoras's (√2): Digit 2,521 = 4
ln 2 — Natural log of 2: Digit 2,521 = 2
γ — Euler-Mascheroni (γ): Digit 2,521 = 7

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 2,503 (gap of 18)
Next prime: 2,531 (gap of 10)

Hex color

#0009D9

RGB(0, 9, 217)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.9.217.

Address: 0.0.9.217
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.9.217

Unspecified address (0.0.0.0/8) — "this network" placeholder.

Musical pitch

Heard as a frequency, 2,521 Hz is closest to:

Concert pitch (A4 = 440 Hz): D♯7 (2489 Hz, +22¢)
Scientific pitch (C4 = 256 Hz): E7 (2580.3 Hz, -40¢)
Baroque pitch (A4 = 415 Hz): E7 (2487.2 Hz, +23¢)

Position in π

The digit sequence 2521 first appears in π at position 2,425 of the decimal expansion (the 2,425ordinal-suffix:th digit after the integer 3).

Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.

Look up 2521 on Pi Search ↗