668637 has 6 divisors (see below), whose sum is σ = 965822. Its totient is φ = 445752.

The previous prime is 668623. The next prime is 668671. The reversal of 668637 is 736866.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 367236 + 301401 = 606^2 + 549^2 .

It is not a de Polignac number, because 668637 - 2⁷ = 668509 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 668637.

It is not an unprimeable number, because it can be changed into a prime (668617) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 37138 + ... + 37155.

2⁶⁶⁸⁶³⁷ is an apocalyptic number.

It is an amenable number.

668637 is a deficient number, since it is larger than the sum of its proper divisors (297185).

668637 is a wasteful number, since it uses less digits than its factorization.

668637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74299 (or 74296 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 668637 is about 817.7022685550. The cubic root of 668637 is about 87.4440240624. Note that the first 3 decimals are identical.

The spelling of 668637 in words is "six hundred sixty-eight thousand, six hundred thirty-seven".