215138857 has 2 divisors, whose sum is σ = 215138858. Its totient is φ = 215138856.

The previous prime is 215138813. The next prime is 215138867. The reversal of 215138857 is 758831512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173290896 + 41847961 = 13164^2 + 6469^2 .

It is a cyclic number.

It is not a de Polignac number, because 215138857 - 2¹¹ = 215136809 is a prime.

It is not a weakly prime, because it can be changed into another prime (215138867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107569428 + 107569429.

It is an arithmetic number, because the mean of its divisors is an integer number (107569429).

Almost surely, 2^215138857 is an apocalyptic number.

It is an amenable number.

215138857 is a deficient number, since it is larger than the sum of its proper divisors (1).

215138857 is an equidigital number, since it uses as much as digits as its factorization.

215138857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 67200, while the sum is 40.

The square root of 215138857 is about 14667.6125187435. The cubic root of 215138857 is about 599.2015833932.

The spelling of 215138857 in words is "two hundred fifteen million, one hundred thirty-eight thousand, eight hundred fifty-seven".