215107657209 has 45 divisors (see below), whose sum is σ = 332983602237. Its totient is φ = 138382183296.

The previous prime is 215107657189. The next prime is 215107657211. The reversal of 215107657209 is 902756701512.

The square root of 215107657209 is 463797.

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

215107657209 is a `hidden beast` number, since 2 + 1 + 5 + 1 + 0 + 76 + 572 + 0 + 9 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 208658025 + 214898999184 = 14445^2 + 463572^2 .

It is not a de Polignac number, because 215107657209 - 2²⁵ = 215074102777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (215107657309) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 121050129 + ... + 121051905.

Almost surely, 2^215107657209 is an apocalyptic number.

215107657209 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

215107657209 is the 463797-th square number.

215107657209 is the 231899-th centered octagonal number.

It is an amenable number.

215107657209 is a deficient number, since it is larger than the sum of its proper divisors (117875945028).

215107657209 is an frugal number, since it uses more digits than its factorization.

215107657209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3624 (or 1809 counting only the distinct ones).

The product of its (nonzero) digits is 264600, while the sum is 45.

The spelling of 215107657209 in words is "two hundred fifteen billion, one hundred seven million, six hundred fifty-seven thousand, two hundred nine".