663245981 has 2 divisors, whose sum is σ = 663245982. Its totient is φ = 663245980.

The previous prime is 663245959. The next prime is 663246013. The reversal of 663245981 is 189542366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 382984900 + 280261081 = 19570^2 + 16741^2 .

It is a cyclic number.

It is not a de Polignac number, because 663245981 - 2²² = 659051677 is a prime.

It is a super-2 number, since 2×663245981² = 879790462625304722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (663245911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331622990 + 331622991.

It is an arithmetic number, because the mean of its divisors is an integer number (331622991).

Almost surely, 2^663245981 is an apocalyptic number.

It is an amenable number.

663245981 is a deficient number, since it is larger than the sum of its proper divisors (1).

663245981 is an equidigital number, since it uses as much as digits as its factorization.

663245981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 311040, while the sum is 44.

The square root of 663245981 is about 25753.5624914302. The cubic root of 663245981 is about 872.0837798786.

The spelling of 663245981 in words is "six hundred sixty-three million, two hundred forty-five thousand, nine hundred eighty-one".