81981288974 has 32 divisors (see below), whose sum is σ = 133915965120. Its totient is φ = 37415688192.

The previous prime is 81981288947. The next prime is 81981289001. The reversal of 81981288974 is 47988218918.

It is an interprime number because it is at equal distance from previous prime (81981288947) and next prime (81981289001).

It is a self number, because there is not a number n which added to its sum of digits gives 81981288974.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 789092 + ... + 886920.

It is an arithmetic number, because the mean of its divisors is an integer number (4184873910).

Almost surely, 2^81981288974 is an apocalyptic number.

81981288974 is a deficient number, since it is larger than the sum of its proper divisors (51934676146).

81981288974 is a wasteful number, since it uses less digits than its factorization.

81981288974 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98204.

The product of its digits is 18579456, while the sum is 65.

The spelling of 81981288974 in words is "eighty-one billion, nine hundred eighty-one million, two hundred eighty-eight thousand, nine hundred seventy-four".