215855609 has 2 divisors, whose sum is σ = 215855610. Its totient is φ = 215855608.

The previous prime is 215855587. The next prime is 215855623. The reversal of 215855609 is 906558512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 213744400 + 2111209 = 14620^2 + 1453^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215855609 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (215855659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107927804 + 107927805.

It is an arithmetic number, because the mean of its divisors is an integer number (107927805).

Almost surely, 2^215855609 is an apocalyptic number.

It is an amenable number.

215855609 is a deficient number, since it is larger than the sum of its proper divisors (1).

215855609 is an equidigital number, since it uses as much as digits as its factorization.

215855609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108000, while the sum is 41.

The square root of 215855609 is about 14692.0253539122. The cubic root of 215855609 is about 599.8662748278.

The spelling of 215855609 in words is "two hundred fifteen million, eight hundred fifty-five thousand, six hundred nine".