81606915 has 48 divisors (see below), whose sum is σ = 153316800. Its totient is φ = 39916800.

The previous prime is 81606869. The next prime is 81606937. The reversal of 81606915 is 51960618.

It is not a de Polignac number, because 81606915 - 2⁹ = 81606403 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81606915.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 116065 + ... + 116765.

It is an arithmetic number, because the mean of its divisors is an integer number (3194100).

Almost surely, 2^81606915 is an apocalyptic number.

81606915 is a deficient number, since it is larger than the sum of its proper divisors (71709885).

81606915 is a wasteful number, since it uses less digits than its factorization.

81606915 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924 (or 921 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 81606915 is about 9033.6545760838. The cubic root of 81606915 is about 433.7528288122.

The spelling of 81606915 in words is "eighty-one million, six hundred six thousand, nine hundred fifteen".