81932192644 has 27 divisors (see below), whose sum is σ = 144413559493. Its totient is φ = 40673274848.

The previous prime is 81932192623. The next prime is 81932192651. The reversal of 81932192644 is 44629123918.

It is a happy number.

The square root of 81932192644 is 286238.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 75927802500 + 6004390144 = 275550^2 + 77488^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 95603064 + ... + 95603920.

Almost surely, 2^81932192644 is an apocalyptic number.

81932192644 is the 286238-th square number.

It is an amenable number.

81932192644 is a deficient number, since it is larger than the sum of its proper divisors (62481366849).

81932192644 is an frugal number, since it uses more digits than its factorization.

81932192644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2052 (or 1026 counting only the distinct ones).

The product of its digits is 746496, while the sum is 49.

Multiplying 81932192644 by its sum of digits (49), we get a square (4014677439556 = 2003666²).

It can be divided in two parts, 81932 and 192644, that added together give a square (274576 = 524²).

The spelling of 81932192644 in words is "eighty-one billion, nine hundred thirty-two million, one hundred ninety-two thousand, six hundred forty-four".