6631 has 4 divisors (see below), whose sum is σ = 7000. Its totient is φ = 6264.

The previous prime is 6619. The next prime is 6637. The reversal of 6631 is 1366.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1366 = 2 ⋅683.

It is a cyclic number.

It is not a de Polignac number, because 6631 - 2⁵ = 6599 is a prime.

It is a super-2 number, since 2×6631² = 87940322, which contains 22 as substring.

It is a Duffinian number.

6631 is a lucky number.

It is a nialpdrome in base 10.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6637) 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, 156 + ... + 193.

It is an arithmetic number, because the mean of its divisors is an integer number (1750).

2⁶⁶³¹ is an apocalyptic number.

6631 is the 52-nd centered pentagonal number.

6631 is a deficient number, since it is larger than the sum of its proper divisors (369).

6631 is a wasteful number, since it uses less digits than its factorization.

6631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 368.

The product of its digits is 108, while the sum is 16.

The square root of 6631 is about 81.4309523461. The cubic root of 6631 is about 18.7870969256.

Adding to 6631 its reverse (1366), we get a palindrome (7997).

The spelling of 6631 in words is "six thousand, six hundred thirty-one".