165720639744 has 405 divisors, whose sum is σ = 545277139561. Its totient is φ = 50022973440.

The previous prime is 165720639737. The next prime is 165720639757. The reversal of 165720639744 is 447936027561.

The square root of 165720639744 is 407088.

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

165720639744 is a `hidden beast` number, since 1 + 6 + 5 + 7 + 206 + 397 + 44 = 666.

It can be written as a sum of positive squares in only one way, i.e., 163151366400 + 2569273344 = 403920^2 + 50688^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 644827264 + ... + 644827520.

Almost surely, 2^165720639744 is an apocalyptic number.

165720639744 is the 407088-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 165720639744

165720639744 is an abundant number, since it is smaller than the sum of its proper divisors (379556499817).

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

165720639744 is an frugal number, since it uses more digits than its factorization.

165720639744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 7620480, while the sum is 54.

The spelling of 165720639744 in words is "one hundred sixty-five billion, seven hundred twenty million, six hundred thirty-nine thousand, seven hundred forty-four".