81657996 has 24 divisors (see below), whose sum is σ = 217754880. Its totient is φ = 23330832.

The previous prime is 81657977. The next prime is 81658007. The reversal of 81657996 is 69975618.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 485976 + ... + 486143.

It is an arithmetic number, because the mean of its divisors is an integer number (9073120).

Almost surely, 2^81657996 is an apocalyptic number.

It is an amenable number.

81657996 is an abundant number, since it is smaller than the sum of its proper divisors (136096884).

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

81657996 is a wasteful number, since it uses less digits than its factorization.

81657996 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 972133 (or 972131 counting only the distinct ones).

The product of its digits is 816480, while the sum is 51.

The square root of 81657996 is about 9036.4813948793. The cubic root of 81657996 is about 433.8433109605.

It can be divided in two parts, 8165 and 7996, that added together give a palindrome (16161).

The spelling of 81657996 in words is "eighty-one million, six hundred fifty-seven thousand, nine hundred ninety-six".