81985836 has 24 divisors (see below), whose sum is σ = 201369280. Its totient is φ = 25890192.

The previous prime is 81985819. The next prime is 81985847. The reversal of 81985836 is 63858918.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 179566 + ... + 180021.

Almost surely, 2^81985836 is an apocalyptic number.

It is an amenable number.

81985836 is an abundant number, since it is smaller than the sum of its proper divisors (119383444).

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

81985836 is a wasteful number, since it uses less digits than its factorization.

81985836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359613 (or 359611 counting only the distinct ones).

The product of its digits is 414720, while the sum is 48.

The square root of 81985836 is about 9054.6030282945. The cubic root of 81985836 is about 434.4231328130.

The spelling of 81985836 in words is "eighty-one million, nine hundred eighty-five thousand, eight hundred thirty-six".