81515625 has 56 divisors (see below), whose sum is σ = 142498176. Its totient is φ = 41400000.

The previous prime is 81515591. The next prime is 81515627. The reversal of 81515625 is 52651518.

It is not a de Polignac number, because 81515625 - 2¹⁵ = 81482857 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81515627) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 1734352 + ... + 1734398.

Almost surely, 2^81515625 is an apocalyptic number.

It is an amenable number.

81515625 is a deficient number, since it is larger than the sum of its proper divisors (60982551).

81515625 is an frugal number, since it uses more digits than its factorization.

81515625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117 (or 92 counting only the distinct ones).

The product of its digits is 12000, while the sum is 33.

The square root of 81515625 is about 9028.6003898722. The cubic root of 81515625 is about 433.5910285114.

The spelling of 81515625 in words is "eighty-one million, five hundred fifteen thousand, six hundred twenty-five".