81872164 has 12 divisors (see below), whose sum is σ = 156301488. Its totient is φ = 37214600.

The previous prime is 81872143. The next prime is 81872207. The reversal of 81872164 is 46127818.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 930322 + ... + 930409.

It is an arithmetic number, because the mean of its divisors is an integer number (13025124).

Almost surely, 2^81872164 is an apocalyptic number.

It is an amenable number.

81872164 is a deficient number, since it is larger than the sum of its proper divisors (74429324).

81872164 is a wasteful number, since it uses less digits than its factorization.

81872164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1860746 (or 1860744 counting only the distinct ones).

The product of its digits is 21504, while the sum is 37.

The square root of 81872164 is about 9048.3238226757. The cubic root of 81872164 is about 434.2222664655. Note that the first 4 decimals are identical.

The spelling of 81872164 in words is "eighty-one million, eight hundred seventy-two thousand, one hundred sixty-four".