663343991 has 2 divisors, whose sum is σ = 663343992. Its totient is φ = 663343990.

The previous prime is 663343969. The next prime is 663344009. The reversal of 663343991 is 199343366.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663343991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (663343691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331671995 + 331671996.

It is an arithmetic number, because the mean of its divisors is an integer number (331671996).

Almost surely, 2^663343991 is an apocalyptic number.

663343991 is a deficient number, since it is larger than the sum of its proper divisors (1).

663343991 is an equidigital number, since it uses as much as digits as its factorization.

663343991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 44.

The square root of 663343991 is about 25755.4652646773. The cubic root of 663343991 is about 872.1267346414.

The spelling of 663343991 in words is "six hundred sixty-three million, three hundred forty-three thousand, nine hundred ninety-one".