Properties of the Number 91380

Ninety-One Thousand Three Hundred Eighty

Basics

Value: 91379 → 91380 → 91381

Parity: even

Prime: No

Previous Prime: 91373

Next Prime: 91381

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 2 ² × 3 × 5 × 1523

Divisors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 10110010011110100

Octal: 262364

Duodecimal: 44A70

Hexadecimal: 164f4

Square: 8350304400

Square Root: 302.2912502868715

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

Least k such that H(k) > n, where H(k) is the harmonic number ∑_i=1..k 1/i. A2387

Least k such that H(k) >= n, where H(k) is the harmonic number ∑_i=1..k 1/i. A4080

Number of books required for n book-lengths of overhang in the harmonic book stacking problem. ∑_i=1..a(n) 1/i >= 2n and ∑_i=1..a(n)-1 1/i < 2n. A14537

E.g.f. satisfies: A(x) = 1/(1-x)^A(x³). A264408

Least positive integer k such that 1 + 1/2 + ... + 1/k > n/2. A226161

1 followed by the union of the terms > 2 in A002387 (or A004080) and A115515. A242654

Numbers k such that if 2 <= j < k then the fractional part of the k-th partial sum of the harmonic series is < the fractional part of the j-th partial sum of the harmonic series. A4796

Least n such that H(n) is closer to an integer than any H(j) with j < n; where H(n) is the harmonic number ∑_i=0..n 1/i. A87460

a(n) = 1 if a(n-1) is prime, else a(n) = a(n-2)+a(n-3); starting with a(0) = 0, a(1) = a(2) = 1. A142884

Least positive integer k such that 1 + 1/2 + ... + 1/k > n/3. A226187