81708916 has 6 divisors (see below), whose sum is σ = 142990610. Its totient is φ = 40854456.

The previous prime is 81708883. The next prime is 81708917. The reversal of 81708916 is 61980718.

It can be written as a sum of positive squares in only one way, i.e., 63680400 + 18028516 = 7980^2 + 4246^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81708917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10213611 + ... + 10213618.

Almost surely, 2^81708916 is an apocalyptic number.

It is an amenable number.

81708916 is a deficient number, since it is larger than the sum of its proper divisors (61281694).

81708916 is a wasteful number, since it uses less digits than its factorization.

81708916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20427233 (or 20427231 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 40.

The square root of 81708916 is about 9039.2984241035. The cubic root of 81708916 is about 433.9334703742.

The spelling of 81708916 in words is "eighty-one million, seven hundred eight thousand, nine hundred sixteen".