81988992 has 48 divisors (see below), whose sum is σ = 235935180. Its totient is φ = 27329280.

The previous prime is 81988979. The next prime is 81989023. The reversal of 81988992 is 29988918.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 34434 + ... + 36737.

Almost surely, 2^81988992 is an apocalyptic number.

It is an amenable number.

81988992 is an abundant number, since it is smaller than the sum of its proper divisors (153946188).

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

81988992 is a wasteful number, since it uses less digits than its factorization.

81988992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71191 (or 71176 counting only the distinct ones).

The product of its digits is 746496, while the sum is 54.

The square root of 81988992 is about 9054.7773026177. Note that the first 3 decimals coincide. The cubic root of 81988992 is about 434.4287070352.

The spelling of 81988992 in words is "eighty-one million, nine hundred eighty-eight thousand, nine hundred ninety-two".