81974431 has 16 divisors (see below), whose sum is σ = 103150080. Its totient is φ = 63283680.

The previous prime is 81974363. The next prime is 81974437. The reversal of 81974431 is 13447918.

It is a cyclic number.

It is not a de Polignac number, because 81974431 - 2⁹ = 81973919 is a prime.

It is a super-2 number, since 2×81974431² = 13439614675547522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81974437) 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, 3510 + ... + 13276.

It is an arithmetic number, because the mean of its divisors is an integer number (6446880).

Almost surely, 2^81974431 is an apocalyptic number.

81974431 is a deficient number, since it is larger than the sum of its proper divisors (21175649).

81974431 is a wasteful number, since it uses less digits than its factorization.

81974431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9894.

The product of its digits is 24192, while the sum is 37.

The square root of 81974431 is about 9053.9732162184. The cubic root of 81974431 is about 434.4029877659.

The spelling of 81974431 in words is "eighty-one million, nine hundred seventy-four thousand, four hundred thirty-one".