640289440 has 96 divisors (see below), whose sum is σ = 1775620224. Its totient is φ = 213580800.

The previous prime is 640289401. The next prime is 640289467. The reversal of 640289440 is 44982046.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a self number, because there is not a number n which added to its sum of digits gives 640289440.

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, 33715 + ... + 49165.

It is an arithmetic number, because the mean of its divisors is an integer number (18496044).

Almost surely, 2^640289440 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 640289440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (887810112).

640289440 is an abundant number, since it is smaller than the sum of its proper divisors (1135330784).

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

640289440 is a wasteful number, since it uses less digits than its factorization.

640289440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15510 (or 15502 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 37.

The square root of 640289440 is about 25303.9411949996. The cubic root of 640289440 is about 861.9037688452.

The spelling of 640289440 in words is "six hundred forty million, two hundred eighty-nine thousand, four hundred forty".