81515612 has 24 divisors (see below), whose sum is σ = 151457040. Its totient is φ = 38255360.

The previous prime is 81515591. The next prime is 81515627. The reversal of 81515612 is 21651518.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27062 + ... + 29922.

It is an arithmetic number, because the mean of its divisors is an integer number (6310710).

Almost surely, 2^81515612 is an apocalyptic number.

It is an amenable number.

81515612 is a deficient number, since it is larger than the sum of its proper divisors (69941428).

81515612 is a wasteful number, since it uses less digits than its factorization.

81515612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3301 (or 3299 counting only the distinct ones).

The product of its digits is 2400, while the sum is 29.

The square root of 81515612 is about 9028.5996699377. The cubic root of 81515612 is about 433.5910054619.

The spelling of 81515612 in words is "eighty-one million, five hundred fifteen thousand, six hundred twelve".