640431652 has 24 divisors (see below), whose sum is σ = 1296300096. Its totient is φ = 271162848.

The previous prime is 640431643. The next prime is 640431661. The reversal of 640431652 is 256134046.

It is an interprime number because it is at equal distance from previous prime (640431643) and next prime (640431661).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 135463 + ... + 140110.

It is an arithmetic number, because the mean of its divisors is an integer number (54012504).

Almost surely, 2^640431652 is an apocalyptic number.

It is an amenable number.

640431652 is an abundant number, since it is smaller than the sum of its proper divisors (655868444).

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

640431652 is a wasteful number, since it uses less digits than its factorization.

640431652 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 275667 (or 275665 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 640431652 is about 25306.7511150681. The cubic root of 640431652 is about 861.9675753976.

Adding to 640431652 its reverse (256134046), we get a palindrome (896565698).

The spelling of 640431652 in words is "six hundred forty million, four hundred thirty-one thousand, six hundred fifty-two".