215878913 has 2 divisors, whose sum is σ = 215878914. Its totient is φ = 215878912.

The previous prime is 215878889. The next prime is 215878919. The reversal of 215878913 is 319878512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208167184 + 7711729 = 14428^2 + 2777^2 .

It is a cyclic number.

It is not a de Polignac number, because 215878913 - 2¹⁰ = 215877889 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (215878919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107939456 + 107939457.

It is an arithmetic number, because the mean of its divisors is an integer number (107939457).

Almost surely, 2^215878913 is an apocalyptic number.

It is an amenable number.

215878913 is a deficient number, since it is larger than the sum of its proper divisors (1).

215878913 is an equidigital number, since it uses as much as digits as its factorization.

215878913 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 44.

The square root of 215878913 is about 14692.8184158112. The cubic root of 215878913 is about 599.8878614503.

The spelling of 215878913 in words is "two hundred fifteen million, eight hundred seventy-eight thousand, nine hundred thirteen".