81077931 has 12 divisors (see below), whose sum is σ = 127759320. Its totient is φ = 49138080.

The previous prime is 81077929. The next prime is 81077933. The reversal of 81077931 is 13977018.

It is an interprime number because it is at equal distance from previous prime (81077929) and next prime (81077933).

It is not a de Polignac number, because 81077931 - 2¹ = 81077929 is a prime.

It is a super-2 number, since 2×81077931² = 13147261790481522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81077933) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 409386 + ... + 409583.

It is an arithmetic number, because the mean of its divisors is an integer number (10646610).

Almost surely, 2^81077931 is an apocalyptic number.

81077931 is a deficient number, since it is larger than the sum of its proper divisors (46681389).

81077931 is a wasteful number, since it uses less digits than its factorization.

81077931 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 818986 (or 818983 counting only the distinct ones).

The product of its (nonzero) digits is 10584, while the sum is 36.

The square root of 81077931 is about 9004.3284591356. The cubic root of 81077931 is about 432.8135870487.

The spelling of 81077931 in words is "eighty-one million, seventy-seven thousand, nine hundred thirty-one".