81915843 has 16 divisors (see below), whose sum is σ = 115831296. Its totient is φ = 51315840.

The previous prime is 81915833. The next prime is 81915871. The reversal of 81915843 is 34851918.

It is a de Polignac number, because none of the positive numbers 2^k-81915843 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81915833) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53458 + ... + 54968.

It is an arithmetic number, because the mean of its divisors is an integer number (7239456).

Almost surely, 2^81915843 is an apocalyptic number.

81915843 is a deficient number, since it is larger than the sum of its proper divisors (33915453).

81915843 is a wasteful number, since it uses less digits than its factorization.

81915843 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2594.

The product of its digits is 34560, while the sum is 39.

The square root of 81915843 is about 9050.7371522987. The cubic root of 81915843 is about 434.2994722848.

The spelling of 81915843 in words is "eighty-one million, nine hundred fifteen thousand, eight hundred forty-three".