165972900004209 has 81 divisors (see below), whose sum is σ = 249586667249283. Its totient is φ = 106278335501184.

The previous prime is 165972900004169. The next prime is 165972900004211. The reversal of 165972900004209 is 902400009279561.

The square root of 165972900004209 is 12883047.

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

165972900004209 is a `hidden beast` number, since 1 + 6 + 597 + 2 + 9 + 0 + 0 + 0 + 0 + 42 + 0 + 9 = 666.

It can be written as a sum of positive squares in 13 ways, for example, as 44423598000609 + 121549302003600 = 6665103^2 + 11024940^2 .

It is not a de Polignac number, because 165972900004209 - 2⁷ = 165972900004081 is a prime.

It is not an unprimeable number, because it can be changed into a prime (165972900006209) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 418067757999 + ... + 418067758395.

Almost surely, 2^{165972900004209} is an apocalyptic number.

165972900004209 is the 12883047-th square number.

165972900004209 is the 6441524-th centered octagonal number.

It is an amenable number.

165972900004209 is a deficient number, since it is larger than the sum of its proper divisors (83613767245074).

165972900004209 is an frugal number, since it uses more digits than its factorization.

165972900004209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1604 (or 802 counting only the distinct ones).

The product of its (nonzero) digits is 2449440, while the sum is 54.

The spelling of 165972900004209 in words is "one hundred sixty-five trillion, nine hundred seventy-two billion, nine hundred million, four thousand, two hundred nine".