215899993 has 2 divisors, whose sum is σ = 215899994. Its totient is φ = 215899992.

The previous prime is 215899961. The next prime is 215899997. The reversal of 215899993 is 399998512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 156425049 + 59474944 = 12507^2 + 7712^2 .

It is a cyclic number.

It is not a de Polignac number, because 215899993 - 2⁵ = 215899961 is a prime.

It is a super-2 number, since 2×215899993² = 93225613954800098, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (215899997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107949996 + 107949997.

It is an arithmetic number, because the mean of its divisors is an integer number (107949997).

Almost surely, 2^215899993 is an apocalyptic number.

It is an amenable number.

215899993 is a deficient number, since it is larger than the sum of its proper divisors (1).

215899993 is an equidigital number, since it uses as much as digits as its factorization.

215899993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1574640, while the sum is 55.

The square root of 215899993 is about 14693.5357555627. The cubic root of 215899993 is about 599.9073866313.

The spelling of 215899993 in words is "two hundred fifteen million, eight hundred ninety-nine thousand, nine hundred ninety-three".