81637631999 has 32 divisors (see below), whose sum is σ = 108232091136. Its totient is φ = 59614571520.

The previous prime is 81637631993. The next prime is 81637632029. The reversal of 81637631999 is 99913673618.

It is not a de Polignac number, because 81637631999 - 2⁸ = 81637631743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81637631993) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 171164 + ... + 438830.

It is an arithmetic number, because the mean of its divisors is an integer number (3382252848).

Almost surely, 2^81637631999 is an apocalyptic number.

81637631999 is a deficient number, since it is larger than the sum of its proper divisors (26594459137).

81637631999 is a wasteful number, since it uses less digits than its factorization.

81637631999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267935.

The product of its digits is 13226976, while the sum is 62.

The spelling of 81637631999 in words is "eighty-one billion, six hundred thirty-seven million, six hundred thirty-one thousand, nine hundred ninety-nine".