81972270864 has 315 divisors, whose sum is σ = 262829041797. Its totient is φ = 24737011200.

The previous prime is 81972270851. The next prime is 81972270923. The reversal of 81972270864 is 46807227918.

It is a happy number.

The square root of 81972270864 is 286308.

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., 61648917264 + 20323353600 = 248292^2 + 142560^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 81972270864.

It is an unprimeable number.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 340133784 + ... + 340134024.

Almost surely, 2^81972270864 is an apocalyptic number.

81972270864 is the 286308-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81972270864

81972270864 is an abundant number, since it is smaller than the sum of its proper divisors (180856770933).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81972270864 is an equidigital number, since it uses as much as digits as its factorization.

81972270864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 530 (or 257 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 54.

It can be divided in two parts, 81972 and 270864, that added together give a square (352836 = 594²).

The spelling of 81972270864 in words is "eighty-one billion, nine hundred seventy-two million, two hundred seventy thousand, eight hundred sixty-four".