81986364 has 48 divisors (see below), whose sum is σ = 219895200. Its totient is φ = 26385408.

The previous prime is 81986357. The next prime is 81986369. The reversal of 81986364 is 46368918.

81986364 is a `hidden beast` number, since 8 + 1 + 9 + 8 + 636 + 4 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81986369) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9957 + ... + 16220.

It is an arithmetic number, because the mean of its divisors is an integer number (4581150).

Almost surely, 2^81986364 is an apocalyptic number.

It is an amenable number.

81986364 is an abundant number, since it is smaller than the sum of its proper divisors (137908836).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81986364 is a wasteful number, since it uses less digits than its factorization.

81986364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26219 (or 26211 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 81986364 is about 9054.6321846887. The cubic root of 81986364 is about 434.4240653925.

The spelling of 81986364 in words is "eighty-one million, nine hundred eighty-six thousand, three hundred sixty-four".