81369915 has 32 divisors (see below), whose sum is σ = 142926336. Its totient is φ = 39202560.

The previous prime is 81369907. The next prime is 81369923. The reversal of 81369915 is 51996318.

It is an interprime number because it is at equal distance from previous prime (81369907) and next prime (81369923).

It is not a de Polignac number, because 81369915 - 2³ = 81369907 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26079 + ... + 29031.

It is an arithmetic number, because the mean of its divisors is an integer number (4466448).

Almost surely, 2^81369915 is an apocalyptic number.

81369915 is a deficient number, since it is larger than the sum of its proper divisors (61556421).

81369915 is a wasteful number, since it uses less digits than its factorization.

81369915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3139.

The product of its digits is 58320, while the sum is 42.

The square root of 81369915 is about 9020.5274236045. The cubic root of 81369915 is about 433.3325249821.

The spelling of 81369915 in words is "eighty-one million, three hundred sixty-nine thousand, nine hundred fifteen".