631639440 has 120 divisors (see below), whose sum is σ = 2173095288. Its totient is φ = 164321280.

The previous prime is 631639423. The next prime is 631639441. The reversal of 631639440 is 44936136.

It can be written as a sum of positive squares in 4 ways, for example, as 82955664 + 548683776 = 9108^2 + 23424^2 .

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 631639395 and 631639404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (631639441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18822 + ... + 40218.

Almost surely, 2^631639440 is an apocalyptic number.

631639440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 631639440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1086547644).

631639440 is an abundant number, since it is smaller than the sum of its proper divisors (1541455848).

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

631639440 is a wasteful number, since it uses less digits than its factorization.

631639440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21457 (or 21448 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 36.

The square root of 631639440 is about 25132.4380035046. The cubic root of 631639440 is about 858.0048575857.

The spelling of 631639440 in words is "six hundred thirty-one million, six hundred thirty-nine thousand, four hundred forty".