81987976 has 32 divisors (see below), whose sum is σ = 179280000. Its totient is φ = 35136528.

The previous prime is 81987949. The next prime is 81987977. The reversal of 81987976 is 67978918.

It is not an unprimeable number, because it can be changed into a prime (81987977) 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, 12196 + ... + 17683.

It is an arithmetic number, because the mean of its divisors is an integer number (5602500).

Almost surely, 2^81987976 is an apocalyptic number.

It is an amenable number.

81987976 is an abundant number, since it is smaller than the sum of its proper divisors (97292024).

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

81987976 is a wasteful number, since it uses less digits than its factorization.

81987976 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29906 (or 29888 counting only the distinct ones).

The product of its digits is 1524096, while the sum is 55.

The square root of 81987976 is about 9054.7211994627. The cubic root of 81987976 is about 434.4269125611.

The spelling of 81987976 in words is "eighty-one million, nine hundred eighty-seven thousand, nine hundred seventy-six".