640304651 has 4 divisors (see below), whose sum is σ = 731776752. Its totient is φ = 548832552.

The previous prime is 640304629. The next prime is 640304657. The reversal of 640304651 is 156403046.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 640304651 - 2¹⁰ = 640303627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (640304657) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45736040 + ... + 45736053.

It is an arithmetic number, because the mean of its divisors is an integer number (182944188).

Almost surely, 2^640304651 is an apocalyptic number.

640304651 is a deficient number, since it is larger than the sum of its proper divisors (91472101).

640304651 is an equidigital number, since it uses as much as digits as its factorization.

640304651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91472100.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 640304651 is about 25304.2417590411. The cubic root of 640304651 is about 861.9105940472.

Adding to 640304651 its reverse (156403046), we get a palindrome (796707697).

The spelling of 640304651 in words is "six hundred forty million, three hundred four thousand, six hundred fifty-one".