81729618172 has 24 divisors (see below), whose sum is σ = 144169147584. Its totient is φ = 40538840832.

The previous prime is 81729618167. The next prime is 81729618181. The reversal of 81729618172 is 27181692718.

It is a hoax number, since the sum of its digits (52) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 764728 + ... + 865024.

It is an arithmetic number, because the mean of its divisors is an integer number (6007047816).

Almost surely, 2^81729618172 is an apocalyptic number.

It is an amenable number.

81729618172 is a deficient number, since it is larger than the sum of its proper divisors (62439529412).

81729618172 is a wasteful number, since it uses less digits than its factorization.

81729618172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101925 (or 101923 counting only the distinct ones).

The product of its digits is 677376, while the sum is 52.

The spelling of 81729618172 in words is "eighty-one billion, seven hundred twenty-nine million, six hundred eighteen thousand, one hundred seventy-two".