640630651 has 2 divisors, whose sum is σ = 640630652. Its totient is φ = 640630650.

The previous prime is 640630643. The next prime is 640630693. The reversal of 640630651 is 156036046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640630651 - 2³ = 640630643 is a prime.

It is not a weakly prime, because it can be changed into another prime (640630621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320315325 + 320315326.

It is an arithmetic number, because the mean of its divisors is an integer number (320315326).

Almost surely, 2^640630651 is an apocalyptic number.

640630651 is a deficient number, since it is larger than the sum of its proper divisors (1).

640630651 is an equidigital number, since it uses as much as digits as its factorization.

640630651 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 31.

The square root of 640630651 is about 25310.6825470986. The cubic root of 640630651 is about 862.0568448363.

Adding to 640630651 its reverse (156036046), we get a palindrome (796666697).

The spelling of 640630651 in words is "six hundred forty million, six hundred thirty thousand, six hundred fifty-one".