631707921 has 12 divisors (see below), whose sum is σ = 982656948. Its totient is φ = 388743264.

The previous prime is 631707907. The next prime is 631707929. The reversal of 631707921 is 129707136.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 68310225 + 563397696 = 8265^2 + 23736^2 .

It is not a de Polignac number, because 631707921 - 2⁵ = 631707889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (631707929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2699490 + ... + 2699723.

It is an arithmetic number, because the mean of its divisors is an integer number (81888079).

Almost surely, 2^631707921 is an apocalyptic number.

It is an amenable number.

631707921 is a deficient number, since it is larger than the sum of its proper divisors (350949027).

631707921 is a wasteful number, since it uses less digits than its factorization.

631707921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5399232 (or 5399229 counting only the distinct ones).

The product of its (nonzero) digits is 15876, while the sum is 36.

The square root of 631707921 is about 25133.8003692239. The cubic root of 631707921 is about 858.0358641504.

The spelling of 631707921 in words is "six hundred thirty-one million, seven hundred seven thousand, nine hundred twenty-one".