81364923 has 12 divisors (see below), whose sum is σ = 121580160. Its totient is φ = 52372656.

The previous prime is 81364919. The next prime is 81364939. The reversal of 81364923 is 32946318.

81364923 is a `hidden beast` number, since 8 + 1 + 3 + 649 + 2 + 3 = 666.

It is not a de Polignac number, because 81364923 - 2² = 81364919 is a prime.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81364123) 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, 155611 + ... + 156132.

It is an arithmetic number, because the mean of its divisors is an integer number (10131680).

Almost surely, 2^81364923 is an apocalyptic number.

81364923 is a deficient number, since it is larger than the sum of its proper divisors (40215237).

81364923 is a wasteful number, since it uses less digits than its factorization.

81364923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 311778 (or 311775 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 81364923 is about 9020.2507171364. The cubic root of 81364923 is about 433.3236632293.

The spelling of 81364923 in words is "eighty-one million, three hundred sixty-four thousand, nine hundred twenty-three".