81706931 has 4 divisors (see below), whose sum is σ = 81782112. Its totient is φ = 81631752.

The previous prime is 81706909. The next prime is 81706939. The reversal of 81706931 is 13960718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81706931 is a prime.

It is a super-2 number, since 2×81706931² = 13352045146877522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81706891 and 81706900.

It is not an unprimeable number, because it can be changed into a prime (81706939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35936 + ... + 38141.

It is an arithmetic number, because the mean of its divisors is an integer number (20445528).

Almost surely, 2^81706931 is an apocalyptic number.

81706931 is a deficient number, since it is larger than the sum of its proper divisors (75181).

81706931 is a wasteful number, since it uses less digits than its factorization.

81706931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75180.

The product of its (nonzero) digits is 9072, while the sum is 35.

The square root of 81706931 is about 9039.1886250924. The cubic root of 81706931 is about 433.9299564169.

The spelling of 81706931 in words is "eighty-one million, seven hundred six thousand, nine hundred thirty-one".