631440 has 60 divisors (see below), whose sum is σ = 2123004. Its totient is φ = 168192.

The previous prime is 631429. The next prime is 631453. The reversal of 631440 is 44136.

It can be written as a sum of positive squares in 2 ways, for example, as 389376 + 242064 = 624^2 + 492^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 631440.

It is an unprimeable number.

631440 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 282 + ... + 1158.

2⁶³¹⁴⁴⁰ is an apocalyptic number.

631440 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 631440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1061502).

631440 is an abundant number, since it is smaller than the sum of its proper divisors (1491564).

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

631440 is a wasteful number, since it uses less digits than its factorization.

631440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 896 (or 887 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 631440 is about 794.6319902949. The cubic root of 631440 is about 85.7914543138.

Adding to 631440 its reverse (44136), we get a palindrome (675576).

The spelling of 631440 in words is "six hundred thirty-one thousand, four hundred forty".