215641561 has 2 divisors, whose sum is σ = 215641562. Its totient is φ = 215641560.

The previous prime is 215641529. The next prime is 215641579. The reversal of 215641561 is 165146512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135001161 + 80640400 = 11619^2 + 8980^2 .

It is a cyclic number.

It is not a de Polignac number, because 215641561 - 2⁵ = 215641529 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (215641501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107820780 + 107820781.

It is an arithmetic number, because the mean of its divisors is an integer number (107820781).

Almost surely, 2^215641561 is an apocalyptic number.

It is an amenable number.

215641561 is a deficient number, since it is larger than the sum of its proper divisors (1).

215641561 is an equidigital number, since it uses as much as digits as its factorization.

215641561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7200, while the sum is 31.

The square root of 215641561 is about 14684.7390511374. The cubic root of 215641561 is about 599.6679282849.

The spelling of 215641561 in words is "two hundred fifteen million, six hundred forty-one thousand, five hundred sixty-one".