81871656 has 32 divisors (see below), whose sum is σ = 209441760. Its totient is φ = 26655552.

The previous prime is 81871633. The next prime is 81871679. The reversal of 81871656 is 65617818.

It is an interprime number because it is at equal distance from previous prime (81871633) and next prime (81871679).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38635 + ... + 40698.

It is an arithmetic number, because the mean of its divisors is an integer number (6545055).

Almost surely, 2^81871656 is an apocalyptic number.

81871656 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

It is an amenable number.

81871656 is an abundant number, since it is smaller than the sum of its proper divisors (127570104).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81871656 is a wasteful number, since it uses less digits than its factorization.

81871656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79385 (or 79381 counting only the distinct ones).

The product of its digits is 80640, while the sum is 42.

The square root of 81871656 is about 9048.2957511346. The cubic root of 81871656 is about 434.2213683769.

The spelling of 81871656 in words is "eighty-one million, eight hundred seventy-one thousand, six hundred fifty-six".