213663743981 has 2 divisors, whose sum is σ = 213663743982. Its totient is φ = 213663743980.

The previous prime is 213663743899. The next prime is 213663744011. The reversal of 213663743981 is 189347366312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 208748472100 + 4915271881 = 456890^2 + 70109^2 .

It is a cyclic number.

It is not a de Polignac number, because 213663743981 - 2¹⁴ = 213663727597 is a prime.

It is a super-2 number, since 2×213663743981² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain 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 (213663743681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106831871990 + 106831871991.

It is an arithmetic number, because the mean of its divisors is an integer number (106831871991).

Almost surely, 2^213663743981 is an apocalyptic number.

It is an amenable number.

213663743981 is a deficient number, since it is larger than the sum of its proper divisors (1).

213663743981 is an equidigital number, since it uses as much as digits as its factorization.

213663743981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3919104, while the sum is 53.

The spelling of 213663743981 in words is "two hundred thirteen billion, six hundred sixty-three million, seven hundred forty-three thousand, nine hundred eighty-one".