215710981 has 2 divisors, whose sum is σ = 215710982. Its totient is φ = 215710980.

The previous prime is 215710969. The next prime is 215710987. The reversal of 215710981 is 189017512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 140801956 + 74909025 = 11866^2 + 8655^2 .

It is a cyclic number.

It is not a de Polignac number, because 215710981 - 2⁵ = 215710949 is a prime.

It is a super-2 number, since 2×215710981² = 93062454647964722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215710987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107855490 + 107855491.

It is an arithmetic number, because the mean of its divisors is an integer number (107855491).

Almost surely, 2^215710981 is an apocalyptic number.

It is an amenable number.

215710981 is a deficient number, since it is larger than the sum of its proper divisors (1).

215710981 is an equidigital number, since it uses as much as digits as its factorization.

215710981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 34.

The square root of 215710981 is about 14687.1025393030. The cubic root of 215710981 is about 599.7322703673.

The spelling of 215710981 in words is "two hundred fifteen million, seven hundred ten thousand, nine hundred eighty-one".