631881945 has 16 divisors (see below), whose sum is σ = 1123345920. Its totient is φ = 337003632.

The previous prime is 631881937. The next prime is 631881961. The reversal of 631881945 is 549188136.

631881945 is a `hidden beast` number, since 631 + 8 + 8 + 1 + 9 + 4 + 5 = 666.

It is not a de Polignac number, because 631881945 - 2³ = 631881937 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 631881945.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2340169 + ... + 2340438.

It is an arithmetic number, because the mean of its divisors is an integer number (70209120).

Almost surely, 2^631881945 is an apocalyptic number.

It is an amenable number.

631881945 is a deficient number, since it is larger than the sum of its proper divisors (491463975).

631881945 is a wasteful number, since it uses less digits than its factorization.

631881945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4680621 (or 4680615 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 631881945 is about 25137.2620824146. The cubic root of 631881945 is about 858.1146479885.

The spelling of 631881945 in words is "six hundred thirty-one million, eight hundred eighty-one thousand, nine hundred forty-five".