81993132 has 72 divisors (see below), whose sum is σ = 234976560. Its totient is φ = 23898240.

The previous prime is 81993101. The next prime is 81993157. The reversal of 81993132 is 23139918.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4282 + ... + 13502.

Almost surely, 2^81993132 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 81993132, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117488280).

81993132 is an abundant number, since it is smaller than the sum of its proper divisors (152983428).

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

81993132 is a wasteful number, since it uses less digits than its factorization.

81993132 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9263 (or 9258 counting only the distinct ones).

The product of its digits is 11664, while the sum is 36.

The square root of 81993132 is about 9055.0059083360. The cubic root of 81993132 is about 434.4360190110.

The spelling of 81993132 in words is "eighty-one million, nine hundred ninety-three thousand, one hundred thirty-two".