688631 has 2 divisors, whose sum is σ = 688632. Its totient is φ = 688630.

The previous prime is 688627. The next prime is 688637. The reversal of 688631 is 136886.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 688631 - 2² = 688627 is a prime.

It is a super-2 number, since 2×688631² = 948425308322, 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 (688637) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344315 + 344316.

It is an arithmetic number, because the mean of its divisors is an integer number (344316).

2⁶⁸⁸⁶³¹ is an apocalyptic number.

688631 is a deficient number, since it is larger than the sum of its proper divisors (1).

688631 is an equidigital number, since it uses as much as digits as its factorization.

688631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6912, while the sum is 32.

The square root of 688631 is about 829.8379359851. The cubic root of 688631 is about 88.3070797340.

The spelling of 688631 in words is "six hundred eighty-eight thousand, six hundred thirty-one".