81918396 has 54 divisors (see below), whose sum is σ = 240884280. Its totient is φ = 23404752.

The previous prime is 81918379. The next prime is 81918401. The reversal of 81918396 is 69381918.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 21456 + ... + 24983.

It is an arithmetic number, because the mean of its divisors is an integer number (4460820).

Almost surely, 2^81918396 is an apocalyptic number.

It is an amenable number.

81918396 is an abundant number, since it is smaller than the sum of its proper divisors (158965884).

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

81918396 is a wasteful number, since it uses less digits than its factorization.

81918396 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46463 (or 46451 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 81918396 is about 9050.8781894355. The cubic root of 81918396 is about 434.3039840495.

The spelling of 81918396 in words is "eighty-one million, nine hundred eighteen thousand, three hundred ninety-six".