81522391712 has 12 divisors (see below), whose sum is σ = 160497208746. Its totient is φ = 40761195840.

The previous prime is 81522391703. The next prime is 81522391723. The reversal of 81522391712 is 21719322518.

It can be written as a sum of positive squares in only one way, i.e., 78245516176 + 3276875536 = 279724^2 + 57244^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81522391712.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1273787339 + ... + 1273787402.

Almost surely, 2^81522391712 is an apocalyptic number.

It is an amenable number.

81522391712 is a deficient number, since it is larger than the sum of its proper divisors (78974817034).

81522391712 is a wasteful number, since it uses less digits than its factorization.

81522391712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2547574751 (or 2547574743 counting only the distinct ones).

The product of its digits is 60480, while the sum is 41.

The spelling of 81522391712 in words is "eighty-one billion, five hundred twenty-two million, three hundred ninety-one thousand, seven hundred twelve".