81585025 has 36 divisors (see below), whose sum is σ = 109715200. Its totient is φ = 60112800.

The previous prime is 81585017. The next prime is 81585041. The reversal of 81585025 is 52058518.

It is a happy number.

It is not a de Polignac number, because 81585025 - 2³ = 81585017 is a prime.

It is a super-2 number, since 2×81585025² = 13312232608501250, which contains 22 as substring.

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 35 ways as a sum of consecutive naturals, for example, 409876 + ... + 410074.

Almost surely, 2^81585025 is an apocalyptic number.

It is an amenable number.

81585025 is a deficient number, since it is larger than the sum of its proper divisors (28130175).

81585025 is a wasteful number, since it uses less digits than its factorization.

81585025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286 (or 258 counting only the distinct ones).

The product of its (nonzero) digits is 16000, while the sum is 34.

The square root of 81585025 is about 9032.4429142951. The cubic root of 81585025 is about 433.7140424810.

The spelling of 81585025 in words is "eighty-one million, five hundred eighty-five thousand, twenty-five".