640623140 has 48 divisors (see below), whose sum is σ = 1406401920. Its totient is φ = 244654080.

The previous prime is 640623127. The next prime is 640623161. The reversal of 640623140 is 41326046.

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, 352835 + ... + 354645.

It is an arithmetic number, because the mean of its divisors is an integer number (29300040).

Almost surely, 2^640623140 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 640623140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (703200960).

640623140 is an abundant number, since it is smaller than the sum of its proper divisors (765778780).

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

640623140 is a wasteful number, since it uses less digits than its factorization.

640623140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2612 (or 2610 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 640623140 is about 25310.5341705781. The cubic root of 640623140 is about 862.0534757945.

Adding to 640623140 its reverse (41326046), we get a palindrome (681949186).

The spelling of 640623140 in words is "six hundred forty million, six hundred twenty-three thousand, one hundred forty".