663631 has 2 divisors, whose sum is σ = 663632. Its totient is φ = 663630.

The previous prime is 663601. The next prime is 663653. The reversal of 663631 is 136366.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 663631 - 2⁵ = 663599 is a prime.

It is a super-2 number, since 2×663631² = 880812208322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 663596 and 663605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (663601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331815 + 331816.

It is an arithmetic number, because the mean of its divisors is an integer number (331816).

2⁶⁶³⁶³¹ is an apocalyptic number.

663631 is a deficient number, since it is larger than the sum of its proper divisors (1).

663631 is an equidigital number, since it uses as much as digits as its factorization.

663631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 25.

The square root of 663631 is about 814.6355013133. The cubic root of 663631 is about 87.2252497510.

Adding to 663631 its reverse (136366), we get a palindrome (799997).

The spelling of 663631 in words is "six hundred sixty-three thousand, six hundred thirty-one".