640861763 has 2 divisors, whose sum is σ = 640861764. Its totient is φ = 640861762.

The previous prime is 640861709. The next prime is 640861769. The reversal of 640861763 is 367168046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640861763 - 2¹² = 640857667 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640861763.

It is not a weakly prime, because it can be changed into another prime (640861769) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320430881 + 320430882.

It is an arithmetic number, because the mean of its divisors is an integer number (320430882).

Almost surely, 2^640861763 is an apocalyptic number.

640861763 is a deficient number, since it is larger than the sum of its proper divisors (1).

640861763 is an equidigital number, since it uses as much as digits as its factorization.

640861763 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 41.

The square root of 640861763 is about 25315.2476385280. The cubic root of 640861763 is about 862.1604967236.

The spelling of 640861763 in words is "six hundred forty million, eight hundred sixty-one thousand, seven hundred sixty-three".