631891 has 6 divisors (see below), whose sum is σ = 684420. Its totient is φ = 583128.

The previous prime is 631889. The next prime is 631901. The reversal of 631891 is 198136.

It is a happy number.

It is not a de Polignac number, because 631891 - 2¹ = 631889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (631861) 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, 1701 + ... + 2038.

It is an arithmetic number, because the mean of its divisors is an integer number (114070).

2⁶³¹⁸⁹¹ is an apocalyptic number.

631891 is a deficient number, since it is larger than the sum of its proper divisors (52529).

631891 is a wasteful number, since it uses less digits than its factorization.

631891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3765 (or 3752 counting only the distinct ones).

The product of its digits is 1296, while the sum is 28.

The square root of 631891 is about 794.9157188029. The cubic root of 631891 is about 85.8118746956.

It can be divided in two parts, 63189 and 1, that added together give a triangular number (63190 = T₃₅₅).

The spelling of 631891 in words is "six hundred thirty-one thousand, eight hundred ninety-one".