81985184 has 24 divisors (see below), whose sum is σ = 162595188. Its totient is φ = 40691200.

The previous prime is 81985181. The next prime is 81985187. The reversal of 81985184 is 48158918.

It is an interprime number because it is at equal distance from previous prime (81985181) and next prime (81985187).

It can be written as a sum of positive squares in 2 ways, for example, as 80496784 + 1488400 = 8972^2 + 1220^2 .

It is not an unprimeable number, because it can be changed into a prime (81985181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4967 + ... + 13734.

Almost surely, 2^81985184 is an apocalyptic number.

It is an amenable number.

81985184 is a deficient number, since it is larger than the sum of its proper divisors (80610004).

81985184 is a wasteful number, since it uses less digits than its factorization.

81985184 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18848 (or 18840 counting only the distinct ones).

The product of its digits is 92160, while the sum is 44.

The square root of 81985184 is about 9054.5670244358. The cubic root of 81985184 is about 434.4219812131.

The spelling of 81985184 in words is "eighty-one million, nine hundred eighty-five thousand, one hundred eighty-four".