81993405974 has 16 divisors (see below), whose sum is σ = 123452952000. Its totient is φ = 40842633024.

The previous prime is 81993405973. The next prime is 81993405997. The reversal of 81993405974 is 47950439918.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81993405971) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 736019 + ... + 840065.

It is an arithmetic number, because the mean of its divisors is an integer number (7715809500).

Almost surely, 2^81993405974 is an apocalyptic number.

81993405974 is a deficient number, since it is larger than the sum of its proper divisors (41459546026).

81993405974 is a wasteful number, since it uses less digits than its factorization.

81993405974 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 105527.

The product of its (nonzero) digits is 9797760, while the sum is 59.

The spelling of 81993405974 in words is "eighty-one billion, nine hundred ninety-three million, four hundred five thousand, nine hundred seventy-four".