81581931232 has 24 divisors (see below), whose sum is σ = 160717023936. Its totient is φ = 40764909312.

The previous prime is 81581931203. The next prime is 81581931271. The reversal of 81581931232 is 23213918518.

It is a happy number.

It is a super-2 number, since 2×81581931232² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 763333 + ... + 863620.

It is an arithmetic number, because the mean of its divisors is an integer number (6696542664).

Almost surely, 2^81581931232 is an apocalyptic number.

It is an amenable number.

81581931232 is a deficient number, since it is larger than the sum of its proper divisors (79135092704).

81581931232 is a wasteful number, since it uses less digits than its factorization.

81581931232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1628530 (or 1628522 counting only the distinct ones).

The product of its digits is 103680, while the sum is 43.

The spelling of 81581931232 in words is "eighty-one billion, five hundred eighty-one million, nine hundred thirty-one thousand, two hundred thirty-two".