81940992 has 80 divisors (see below), whose sum is σ = 249513792. Its totient is φ = 23408640.

The previous prime is 81940981. The next prime is 81940993. The reversal of 81940992 is 29904918.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (81940993) 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, 6942 + ... + 14562.

Almost surely, 2^81940992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81940992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124756896).

81940992 is an abundant number, since it is smaller than the sum of its proper divisors (167572800).

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

81940992 is an equidigital number, since it uses as much as digits as its factorization.

81940992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7649 (or 7633 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 42.

The square root of 81940992 is about 9052.1263800281. The cubic root of 81940992 is about 434.3439125277.

The spelling of 81940992 in words is "eighty-one million, nine hundred forty thousand, nine hundred ninety-two".