640724740 has 24 divisors (see below), whose sum is σ = 1388927232. Its totient is φ = 248022240.

The previous prime is 640724737. The next prime is 640724741. The reversal of 640724740 is 47427046.

It is a junction number, because it is equal to n+sod(n) for n = 640724696 and 640724705.

It is not an unprimeable number, because it can be changed into a prime (640724741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 516094 + ... + 517333.

It is an arithmetic number, because the mean of its divisors is an integer number (57871968).

Almost surely, 2^640724740 is an apocalyptic number.

It is an amenable number.

640724740 is an abundant number, since it is smaller than the sum of its proper divisors (748202492).

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

640724740 is a wasteful number, since it uses less digits than its factorization.

640724740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1033467 (or 1033465 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 34.

The square root of 640724740 is about 25312.5411604604. The cubic root of 640724740 is about 862.0990460099.

The spelling of 640724740 in words is "six hundred forty million, seven hundred twenty-four thousand, seven hundred forty".