640465020631 has 2 divisors, whose sum is σ = 640465020632. Its totient is φ = 640465020630.

The previous prime is 640465020617. The next prime is 640465020649. The reversal of 640465020631 is 136020564046.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640465020631 - 2⁵ = 640465020599 is a prime.

It is a super-2 number, since 2×640465020631² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640465020661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320232510315 + 320232510316.

It is an arithmetic number, because the mean of its divisors is an integer number (320232510316).

Almost surely, 2^640465020631 is an apocalyptic number.

640465020631 is a deficient number, since it is larger than the sum of its proper divisors (1).

640465020631 is an equidigital number, since it uses as much as digits as its factorization.

640465020631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 37.

Adding to 640465020631 its reverse (136020564046), we get a palindrome (776485584677).

The spelling of 640465020631 in words is "six hundred forty billion, four hundred sixty-five million, twenty thousand, six hundred thirty-one".