81993516 has 96 divisors (see below), whose sum is σ = 224985600. Its totient is φ = 22963200.

The previous prime is 81993503. The next prime is 81993553. The reversal of 81993516 is 61539918.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 136585 + ... + 137183.

It is an arithmetic number, because the mean of its divisors is an integer number (2343600).

Almost surely, 2^81993516 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 81993516, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112492800).

81993516 is an abundant number, since it is smaller than the sum of its proper divisors (142992084).

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

81993516 is a wasteful number, since it uses less digits than its factorization.

81993516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 695 (or 693 counting only the distinct ones).

The product of its digits is 58320, while the sum is 42.

The square root of 81993516 is about 9055.0271120522. The cubic root of 81993516 is about 434.4366972108.

The spelling of 81993516 in words is "eighty-one million, nine hundred ninety-three thousand, five hundred sixteen".