640308240 has 400 divisors, whose sum is σ = 2616457536. Its totient is φ = 143078400.

The previous prime is 640308233. The next prime is 640308241. The reversal of 640308240 is 42803046.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (640308241) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 926295 + ... + 926985.

Almost surely, 2^640308240 is an apocalyptic number.

640308240 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 640308240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1308228768).

640308240 is an abundant number, since it is smaller than the sum of its proper divisors (1976149296).

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

640308240 is a wasteful number, since it uses less digits than its factorization.

640308240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 740 (or 725 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 640308240 is about 25304.3126759057. The cubic root of 640308240 is about 861.9122044220.

The spelling of 640308240 in words is "six hundred forty million, three hundred eight thousand, two hundred forty".