215449921 has 2 divisors, whose sum is σ = 215449922. Its totient is φ = 215449920.

The previous prime is 215449877. The next prime is 215449931. The reversal of 215449921 is 129944512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 150405696 + 65044225 = 12264^2 + 8065^2 .

It is a cyclic number.

It is not a de Polignac number, because 215449921 - 2²⁵ = 181895489 is a prime.

It is not a weakly prime, because it can be changed into another prime (215449931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107724960 + 107724961.

It is an arithmetic number, because the mean of its divisors is an integer number (107724961).

Almost surely, 2^215449921 is an apocalyptic number.

It is an amenable number.

215449921 is a deficient number, since it is larger than the sum of its proper divisors (1).

215449921 is an equidigital number, since it uses as much as digits as its factorization.

215449921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 37.

The square root of 215449921 is about 14678.2124592881. The cubic root of 215449921 is about 599.4902346140.

The spelling of 215449921 in words is "two hundred fifteen million, four hundred forty-nine thousand, nine hundred twenty-one".