81315775 has 6 divisors (see below), whose sum is σ = 100831592. Its totient is φ = 65052600.

The previous prime is 81315769. The next prime is 81315799. The reversal of 81315775 is 57751318.

It is not a de Polignac number, because 81315775 - 2²³ = 72927167 is a prime.

It is a super-2 number, since 2×81315775² = 13224510527701250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1626291 + ... + 1626340.

Almost surely, 2^81315775 is an apocalyptic number.

81315775 is a deficient number, since it is larger than the sum of its proper divisors (19515817).

81315775 is a wasteful number, since it uses less digits than its factorization.

81315775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3252641 (or 3252636 counting only the distinct ones).

The product of its digits is 29400, while the sum is 37.

The square root of 81315775 is about 9017.5259910909. The cubic root of 81315775 is about 433.2363967916.

The spelling of 81315775 in words is "eighty-one million, three hundred fifteen thousand, seven hundred seventy-five".