Properties of the Number 651

Six Hundred Fifty-One

Basics

Value: 650 → 651 → 652

Parity: odd

Prime: No

Previous Prime: 647

Next Prime: 653

Digit Sum: 12

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 31

Divisors: 1, 3, 7, 21, 31, 93, 217, 651

Polygonal

Triangular: No

Square: No

Pentagonal: Yes

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1010001011

Octal: 1213

Duodecimal: 463

Hexadecimal: 28b

Square: 423801

Square Root: 25.514701644346147

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

Pentagonal numbers: a(n) = n*(3·n-1)/2. A326

Toothpick sequence (see Comments lines for definition). A139250

a(n) = sigma₂(n): sum of squares of divisors of n. A1157

Central polygonal numbers: a(n) = n² - n + 1. A2061

Generalized pentagonal numbers: m*(3·m - 1)/2, m = 0, +-1, +-2, +-3, .... A1318

Number of fractions in Farey series of order n. A5728

9-gonal (or enneagonal or nonagonal) numbers: a(n) = n*(7·n-5)/2. A1106

Triangle of Gaussian binomial coefficients (or q-binomial coefficients) [n,k] for q = 2. A22166

a(n) = (n⁴ + n)/2 (Row sums of an n X n X n magic cube, when it exists). A27441

Gaussian binomial coefficient [n, 2] for q = 2. A6095