215246818809 has 81 divisors (see below), whose sum is σ = 363471069871. Its totient is φ = 122630471040.

The previous prime is 215246818799. The next prime is 215246818921. The reversal of 215246818809 is 908818642512.

The square root of 215246818809 is 463947.

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

215246818809 is a `hidden beast` number, since 21 + 524 + 6 + 8 + 18 + 80 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 167579703225 + 47667115584 = 409365^2 + 218328^2 .

It is not a de Polignac number, because 215246818809 - 2⁷ = 215246818681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (215246818109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 260273854 + ... + 260274680.

Almost surely, 2^215246818809 is an apocalyptic number.

215246818809 is the 463947-th square number.

215246818809 is the 231974-th centered octagonal number.

It is an amenable number.

215246818809 is a deficient number, since it is larger than the sum of its proper divisors (148224251062).

215246818809 is an equidigital number, since it uses as much as digits as its factorization.

215246818809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1716 (or 858 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 54.

The spelling of 215246818809 in words is "two hundred fifteen billion, two hundred forty-six million, eight hundred eighteen thousand, eight hundred nine".