Properties of the Number -28

Twenty-Eight

Basics

Value: -29 → -28 → -27

Parity: even

Prime: No

Previous Prime:

Next Prime: 1

Digit Sum: 10

Digital Root: 1

Palindrome: No

Factorization: 2 ² × 7

Divisors: 1, 2, 4, 7, 14, 28

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: Yes

Heptagonal: No

Tetrahedral: No

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Representations

Binary: -11100

Octal: -34

Duodecimal: -24

Hexadecimal: -1c

Square: 784

Square Root: 5.291502622129181

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

Triangle read by rows of Stirling numbers of first kind, s(n,k), n >= 1, 1 <= k <= n. A8275

Triangle of Stirling numbers of first kind, s(n,k), n >= 0, 0 <= k <= n. A48994

Deficiency of n, or 2n - (sum of divisors of n). A33879

Dirichlet inverse of Euler totient function (A000010). A23900

Abundance of n, or (sum of divisors of n) - 2n. A33880

Canonical enumeration of integers: interleaved positive and negative integers with zero prepended. A1057

a(0) = 0; thereafter a(n) is the least integer (in absolute value) not yet in the sequence such that the absolute difference between a(n-1) and a(n) is a square; in case of a tie, preference is given to the positive value. A377091

a(n) = 2 - n. A22958

Triangle read by rows, 0 <= k <= n: T(n,k) = binomial(n-[(k+1)/2],[k/2])*(-1)^[(k+1)/2]. A108299

Expansion of sqrt(1 - 4·x) in powers of x. A2420