631738561 has 4 divisors (see below), whose sum is σ = 631857492. Its totient is φ = 631619632.

The previous prime is 631738531. The next prime is 631738573. The reversal of 631738561 is 165837136.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18879025 + 612859536 = 4345^2 + 24756^2 .

It is a cyclic number.

It is not a de Polignac number, because 631738561 - 2¹⁷ = 631607489 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (631738501) 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 3 ways as a sum of consecutive naturals, for example, 51106 + ... + 62251.

It is an arithmetic number, because the mean of its divisors is an integer number (157964373).

Almost surely, 2^631738561 is an apocalyptic number.

It is an amenable number.

631738561 is a deficient number, since it is larger than the sum of its proper divisors (118931).

631738561 is a wasteful number, since it uses less digits than its factorization.

631738561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 118930.

The product of its digits is 90720, while the sum is 40.

The square root of 631738561 is about 25134.4098995779. The cubic root of 631738561 is about 858.0497364865.

The spelling of 631738561 in words is "six hundred thirty-one million, seven hundred thirty-eight thousand, five hundred sixty-one".