631688 has 12 divisors (see below), whose sum is σ = 1188645. Its totient is φ = 314720.

The previous prime is 631681. The next prime is 631711. The reversal of 631688 is 886136.

Added to its reverse (886136) it gives a square (1517824 = 1232²).

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 2 ways, for example, as 611524 + 20164 = 782^2 + 142^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=562.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (631681) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2108 + ... + 2388.

2⁶³¹⁶⁸⁸ is an apocalyptic number.

It is an amenable number.

631688 is a deficient number, since it is larger than the sum of its proper divisors (556957).

631688 is an equidigital number, since it uses as much as digits as its factorization.

631688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568 (or 283 counting only the distinct ones).

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

The square root of 631688 is about 794.7880220537. The cubic root of 631688 is about 85.8026844627.

Multiplying 631688 by its sum of digits (32), we get a square (20214016 = 4496²).

Adding to 631688 its reverse (886136), we get a square (1517824 = 1232²).

The spelling of 631688 in words is "six hundred thirty-one thousand, six hundred eighty-eight".