81672916 has 12 divisors (see below), whose sum is σ = 153922132. Its totient is φ = 37695168.

The previous prime is 81672901. The next prime is 81672917. The reversal of 81672916 is 61927618.

It can be written as a sum of positive squares in 2 ways, for example, as 31404816 + 50268100 = 5604^2 + 7090^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81672917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 785265 + ... + 785368.

Almost surely, 2^81672916 is an apocalyptic number.

It is an amenable number.

81672916 is a deficient number, since it is larger than the sum of its proper divisors (72249216).

81672916 is a wasteful number, since it uses less digits than its factorization.

81672916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1570650 (or 1570648 counting only the distinct ones).

The product of its digits is 36288, while the sum is 40.

The square root of 81672916 is about 9037.3068997351. The cubic root of 81672916 is about 433.8697323290.

The spelling of 81672916 in words is "eighty-one million, six hundred seventy-two thousand, nine hundred sixteen".