213365981 has 2 divisors, whose sum is σ = 213365982. Its totient is φ = 213365980.

The previous prime is 213365951. The next prime is 213365987. The reversal of 213365981 is 189563312.

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., 189502756 + 23863225 = 13766^2 + 4885^2 .

It is a cyclic number.

It is not a de Polignac number, because 213365981 - 2¹⁸ = 213103837 is a prime.

It is a super-2 number, since 2×213365981² = 91050083696184722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (213365987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106682990 + 106682991.

It is an arithmetic number, because the mean of its divisors is an integer number (106682991).

Almost surely, 2^213365981 is an apocalyptic number.

It is an amenable number.

213365981 is a deficient number, since it is larger than the sum of its proper divisors (1).

213365981 is an equidigital number, since it uses as much as digits as its factorization.

213365981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 38880, while the sum is 38.

The square root of 213365981 is about 14607.0524405165. The cubic root of 213365981 is about 597.5511120296.

The spelling of 213365981 in words is "two hundred thirteen million, three hundred sixty-five thousand, nine hundred eighty-one".