215666257 has 2 divisors, whose sum is σ = 215666258. Its totient is φ = 215666256.

The previous prime is 215666249. The next prime is 215666261. The reversal of 215666257 is 752666512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 211964481 + 3701776 = 14559^2 + 1924^2 .

It is a cyclic number.

It is not a de Polignac number, because 215666257 - 2³ = 215666249 is a prime.

It is not a weakly prime, because it can be changed into another prime (215660257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107833128 + 107833129.

It is an arithmetic number, because the mean of its divisors is an integer number (107833129).

Almost surely, 2^215666257 is an apocalyptic number.

It is an amenable number.

215666257 is a deficient number, since it is larger than the sum of its proper divisors (1).

215666257 is an equidigital number, since it uses as much as digits as its factorization.

215666257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 151200, while the sum is 40.

The square root of 215666257 is about 14685.5799000244. The cubic root of 215666257 is about 599.6908194100.

The spelling of 215666257 in words is "two hundred fifteen million, six hundred sixty-six thousand, two hundred fifty-seven".