81646713152 has 14 divisors (see below), whose sum is σ = 162017696538. Its totient is φ = 40823356544.

The previous prime is 81646713133. The next prime is 81646713157. The reversal of 81646713152 is 25131764618.

It can be written as a sum of positive squares in only one way, i.e., 68112648256 + 13534064896 = 260984^2 + 116336^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81646713157) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 637864883 + ... + 637865010.

Almost surely, 2^81646713152 is an apocalyptic number.

It is an amenable number.

81646713152 is a deficient number, since it is larger than the sum of its proper divisors (80370983386).

81646713152 is a wasteful number, since it uses less digits than its factorization.

81646713152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1275729905 (or 1275729895 counting only the distinct ones).

The product of its digits is 241920, while the sum is 44.

The spelling of 81646713152 in words is "eighty-one billion, six hundred forty-six million, seven hundred thirteen thousand, one hundred fifty-two".