Properties of the Number 42991

Forty-Two Thousand Nine Hundred Ninety-One

Basics

Value: 42990 → 42991 → 42992

Parity: odd

Prime: No

Previous Prime: 42989

Next Prime: 43003

Digit Sum: 25

Digital Root: 7

Palindrome: No

Factorization: 13 × 3307

Divisors: 1, 13, 3307, 42991

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 1010011111101111

Octal: 123757

Duodecimal: 20A67

Hexadecimal: a7ef

Square: 1848226081

Square Root: 207.34271147064706

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

Numerators of the convergents given by treating A084580 as continued fraction coefficients after the leading 0. A390651

The base 10 numbers with a digit product > 0 and which when written in bases 3,4,5,6,7,8,9 have two or more other base representations with the same digit product. A331565

Total preorders. A6328

Expansion of (1+x⁴*C²)*C³, where C = (1-(1-4·x)^1/2)/(2·x) is g.f. for Catalan numbers, A000108. A71748

Expansion of ∑_{p prime, i>=2} x^pⁱ/(1 - x^pⁱ) / ∏_j>=1 (1 - x^j). A281611

Primes congruent to {0, 2, 3, 4} (mod 5). A42991

Smallest odd k > 1 such that k·2ⁿ - 1 is a prime number. A247202

Number of 5Xn 0..1 arrays avoiding 0 0 0 and 1 1 1 horizontally and 0 0 1 and 0 1 0 vertically. A207775

Number of (n+2)X(2+2) 0..3 arrays with no row, column, diagonal or antidiagonal in any 3X3 subblock summing to 2 3 6 or 7. A251785

a(n) is the least number k having exactly n representations as m + σ(m), where σ(m) is the sum of the divisors of m. A186273