215661553 has 2 divisors, whose sum is σ = 215661554. Its totient is φ = 215661552.

The previous prime is 215661497. The next prime is 215661569. The reversal of 215661553 is 355166512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 161594944 + 54066609 = 12712^2 + 7353^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215661553 is a prime.

It is not a weakly prime, because it can be changed into another prime (215661583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107830776 + 107830777.

It is an arithmetic number, because the mean of its divisors is an integer number (107830777).

Almost surely, 2^215661553 is an apocalyptic number.

It is an amenable number.

215661553 is a deficient number, since it is larger than the sum of its proper divisors (1).

215661553 is an equidigital number, since it uses as much as digits as its factorization.

215661553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 27000, while the sum is 34.

The square root of 215661553 is about 14685.4197420435. The cubic root of 215661553 is about 599.6864593304.

The spelling of 215661553 in words is "two hundred fifteen million, six hundred sixty-one thousand, five hundred fifty-three".