81571688 has 32 divisors (see below), whose sum is σ = 170739360. Its totient is φ = 36214080.

The previous prime is 81571681. The next prime is 81571703. The reversal of 81571688 is 88617518.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (81571681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6995 + ... + 14562.

It is an arithmetic number, because the mean of its divisors is an integer number (5335605).

Almost surely, 2^81571688 is an apocalyptic number.

81571688 is a gapful number since it is divisible by the number (88) formed by its first and last digit.

It is an amenable number.

81571688 is an abundant number, since it is smaller than the sum of its proper divisors (89167672).

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

81571688 is a wasteful number, since it uses less digits than its factorization.

81571688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21617 (or 21613 counting only the distinct ones).

The product of its digits is 107520, while the sum is 44.

The square root of 81571688 is about 9031.7046010152. The cubic root of 81571688 is about 433.6904075904.

The spelling of 81571688 in words is "eighty-one million, five hundred seventy-one thousand, six hundred eighty-eight".