81606916 has 6 divisors (see below), whose sum is σ = 142812110. Its totient is φ = 40803456.

The previous prime is 81606869. The next prime is 81606937. The reversal of 81606916 is 61960618.

It can be written as a sum of positive squares in only one way, i.e., 72182016 + 9424900 = 8496^2 + 3070^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200861 + ... + 10200868.

Almost surely, 2^81606916 is an apocalyptic number.

It is an amenable number.

81606916 is a deficient number, since it is larger than the sum of its proper divisors (61205194).

81606916 is a wasteful number, since it uses less digits than its factorization.

81606916 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20401733 (or 20401731 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 81606916 is about 9033.6546314324. The cubic root of 81606916 is about 433.7528305839.

The spelling of 81606916 in words is "eighty-one million, six hundred six thousand, nine hundred sixteen".