663031991 has 2 divisors, whose sum is σ = 663031992. Its totient is φ = 663031990.

The previous prime is 663031979. The next prime is 663032059. The reversal of 663031991 is 199130366.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 663031991 - 2¹⁴ = 663015607 is a prime.

It is a super-2 number, since 2×663031991² = 879222842178848162, 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 (663031591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331515995 + 331515996.

It is an arithmetic number, because the mean of its divisors is an integer number (331515996).

Almost surely, 2^663031991 is an apocalyptic number.

663031991 is a deficient number, since it is larger than the sum of its proper divisors (1).

663031991 is an equidigital number, since it uses as much as digits as its factorization.

663031991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26244, while the sum is 38.

The square root of 663031991 is about 25749.4075854183. The cubic root of 663031991 is about 871.9899799476.

The spelling of 663031991 in words is "six hundred sixty-three million, thirty-one thousand, nine hundred ninety-one".