215677993 has 2 divisors, whose sum is σ = 215677994. Its totient is φ = 215677992.

The previous prime is 215677939. The next prime is 215678011. The reversal of 215677993 is 399776512.

Together with previous prime (215677939) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 180311184 + 35366809 = 13428^2 + 5947^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215677993 is a prime.

It is not a weakly prime, because it can be changed into another prime (215677933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107838996 + 107838997.

It is an arithmetic number, because the mean of its divisors is an integer number (107838997).

Almost surely, 2^215677993 is an apocalyptic number.

It is an amenable number.

215677993 is a deficient number, since it is larger than the sum of its proper divisors (1).

215677993 is an equidigital number, since it uses as much as digits as its factorization.

215677993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 714420, while the sum is 49.

The square root of 215677993 is about 14685.9794702294. The cubic root of 215677993 is about 599.7016970872.

The spelling of 215677993 in words is "two hundred fifteen million, six hundred seventy-seven thousand, nine hundred ninety-three".