631618640 has 80 divisors (see below), whose sum is σ = 1540080000. Its totient is φ = 240446976.

The previous prime is 631618639. The next prime is 631618661. The reversal of 631618640 is 46816136.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 631618640.

It is a congruent number.

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, 420611 + ... + 422109.

It is an arithmetic number, because the mean of its divisors is an integer number (19251000).

Almost surely, 2^631618640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 631618640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (770040000).

631618640 is an abundant number, since it is smaller than the sum of its proper divisors (908461360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

631618640 is a wasteful number, since it uses less digits than its factorization.

631618640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1764 (or 1758 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 631618640 is about 25132.0241922532. The cubic root of 631618640 is about 857.9954393978.

The spelling of 631618640 in words is "six hundred thirty-one million, six hundred eighteen thousand, six hundred forty".