81664776 has 48 divisors (see below), whose sum is σ = 221785200. Its totient is φ = 27146592.

The previous prime is 81664771. The next prime is 81664799. The reversal of 81664776 is 67746618.

It is not an unprimeable number, because it can be changed into a prime (81664771) 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, 28815 + ... + 31521.

It is an arithmetic number, because the mean of its divisors is an integer number (4620525).

Almost surely, 2^81664776 is an apocalyptic number.

It is an amenable number.

81664776 is an abundant number, since it is smaller than the sum of its proper divisors (140120424).

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

81664776 is a wasteful number, since it uses less digits than its factorization.

81664776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3138 (or 3131 counting only the distinct ones).

The product of its digits is 338688, while the sum is 45.

The square root of 81664776 is about 9036.8565331093. The cubic root of 81664776 is about 433.8553178527.

The spelling of 81664776 in words is "eighty-one million, six hundred sixty-four thousand, seven hundred seventy-six".