81974538 has 32 divisors (see below), whose sum is σ = 183193920. Its totient is φ = 27170640.

The previous prime is 81974537. The next prime is 81974579. The reversal of 81974538 is 83547918.

81974538 is a `hidden beast` number, since 8 + 197 + 453 + 8 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 81974493 and 81974502.

It is not an unprimeable number, because it can be changed into a prime (81974537) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5581 + ... + 13967.

It is an arithmetic number, because the mean of its divisors is an integer number (5724810).

Almost surely, 2^81974538 is an apocalyptic number.

81974538 is an abundant number, since it is smaller than the sum of its proper divisors (101219382).

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

81974538 is a wasteful number, since it uses less digits than its factorization.

81974538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8579 (or 8573 counting only the distinct ones).

The product of its digits is 241920, while the sum is 45.

The square root of 81974538 is about 9053.9791252244. The cubic root of 81974538 is about 434.4031767723.

It can be divided in two parts, 819 and 74538, that added together give a palindrome (75357).

The spelling of 81974538 in words is "eighty-one million, nine hundred seventy-four thousand, five hundred thirty-eight".