81316992 has 64 divisors (see below), whose sum is σ = 216941760. Its totient is φ = 26987520.

The previous prime is 81316969. The next prime is 81316993. The reversal of 81316992 is 29961318.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×81316992² = 13224906375856128, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81316992.

It is not an unprimeable number, because it can be changed into a prime (81316993) 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, 161413 + ... + 161915.

It is an arithmetic number, because the mean of its divisors is an integer number (3389715).

Almost surely, 2^81316992 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 81316992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108470880).

81316992 is an abundant number, since it is smaller than the sum of its proper divisors (135624768).

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

81316992 is a wasteful number, since it uses less digits than its factorization.

81316992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 941 (or 929 counting only the distinct ones).

The product of its digits is 23328, while the sum is 39.

The square root of 81316992 is about 9017.5934705441. The cubic root of 81316992 is about 433.2385581027.

The spelling of 81316992 in words is "eighty-one million, three hundred sixteen thousand, nine hundred ninety-two".