663663661 has 2 divisors, whose sum is σ = 663663662. Its totient is φ = 663663660.

The previous prime is 663663653. The next prime is 663663667. The reversal of 663663661 is 166366366.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 337861161 + 325802500 = 18381^2 + 18050^2 .

It is a cyclic number.

It is not a de Polignac number, because 663663661 - 2³ = 663663653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (663663667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331831830 + 331831831.

It is an arithmetic number, because the mean of its divisors is an integer number (331831831).

Almost surely, 2^663663661 is an apocalyptic number.

It is an amenable number.

663663661 is a deficient number, since it is larger than the sum of its proper divisors (1).

663663661 is an equidigital number, since it uses as much as digits as its factorization.

663663661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 419904, while the sum is 43.

The square root of 663663661 is about 25761.6703845073. The cubic root of 663663661 is about 872.2668067533.

The spelling of 663663661 in words is "six hundred sixty-three million, six hundred sixty-three thousand, six hundred sixty-one".