215585861 has 2 divisors, whose sum is σ = 215585862. Its totient is φ = 215585860.

The previous prime is 215585849. The next prime is 215585869. The reversal of 215585861 is 168585512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 141729025 + 73856836 = 11905^2 + 8594^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215585861 is a prime.

It is a super-2 number, since 2×215585861² = 92954526926222642, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215585869) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107792930 + 107792931.

It is an arithmetic number, because the mean of its divisors is an integer number (107792931).

Almost surely, 2^215585861 is an apocalyptic number.

It is an amenable number.

215585861 is a deficient number, since it is larger than the sum of its proper divisors (1).

215585861 is an equidigital number, since it uses as much as digits as its factorization.

215585861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 96000, while the sum is 41.

The square root of 215585861 is about 14682.8424019329. The cubic root of 215585861 is about 599.6162926297.

The spelling of 215585861 in words is "two hundred fifteen million, five hundred eighty-five thousand, eight hundred sixty-one".