81972164 has 12 divisors (see below), whose sum is σ = 151889724. Its totient is φ = 38575104.

The previous prime is 81972151. The next prime is 81972167. The reversal of 81972164 is 46127918.

It can be written as a sum of positive squares in 2 ways, for example, as 56550400 + 25421764 = 7520^2 + 5042^2 .

It is not an unprimeable number, because it can be changed into a prime (81972167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 602669 + ... + 602804.

It is an arithmetic number, because the mean of its divisors is an integer number (12657477).

Almost surely, 2^81972164 is an apocalyptic number.

It is an amenable number.

81972164 is a deficient number, since it is larger than the sum of its proper divisors (69917560).

81972164 is a wasteful number, since it uses less digits than its factorization.

81972164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1205494 (or 1205492 counting only the distinct ones).

The product of its digits is 24192, while the sum is 38.

The square root of 81972164 is about 9053.8480216977. The cubic root of 81972164 is about 434.3989832625.

The spelling of 81972164 in words is "eighty-one million, nine hundred seventy-two thousand, one hundred sixty-four".