81939575 has 12 divisors (see below), whose sum is σ = 107582400. Its totient is φ = 61695360.

The previous prime is 81939569. The next prime is 81939601. The reversal of 81939575 is 57593918.

It is not a de Polignac number, because 81939575 - 2²⁴ = 65162359 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 95975 + ... + 96824.

It is an arithmetic number, because the mean of its divisors is an integer number (8965200).

Almost surely, 2^81939575 is an apocalyptic number.

81939575 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81939575 is a deficient number, since it is larger than the sum of its proper divisors (25642825).

81939575 is a wasteful number, since it uses less digits than its factorization.

81939575 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 192826 (or 192821 counting only the distinct ones).

The product of its digits is 340200, while the sum is 47.

The square root of 81939575 is about 9052.0481107869. The cubic root of 81939575 is about 434.3414088200.

The spelling of 81939575 in words is "eighty-one million, nine hundred thirty-nine thousand, five hundred seventy-five".