668631 has 4 divisors (see below), whose sum is σ = 891512. Its totient is φ = 445752.

The previous prime is 668623. The next prime is 668671. The reversal of 668631 is 136866.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 668631 - 2³ = 668623 is a prime.

It is a super-2 number, since 2×668631² = 894134828322, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668611) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 111436 + ... + 111441.

It is an arithmetic number, because the mean of its divisors is an integer number (222878).

2⁶⁶⁸⁶³¹ is an apocalyptic number.

668631 is a deficient number, since it is larger than the sum of its proper divisors (222881).

668631 is a wasteful number, since it uses less digits than its factorization.

668631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222880.

The product of its digits is 5184, while the sum is 30.

The square root of 668631 is about 817.6985997298. The cubic root of 668631 is about 87.4437625026.

The spelling of 668631 in words is "six hundred sixty-eight thousand, six hundred thirty-one".