640631415617 has 2 divisors, whose sum is σ = 640631415618. Its totient is φ = 640631415616.

The previous prime is 640631415569. The next prime is 640631415631. The reversal of 640631415617 is 716514136046.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 578389149361 + 62242266256 = 760519^2 + 249484^2 .

It is a cyclic number.

It is not a de Polignac number, because 640631415617 - 2¹⁸ = 640631153473 is a prime.

It is a super-2 number, since 2×640631415617² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (640631415517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320315707808 + 320315707809.

It is an arithmetic number, because the mean of its divisors is an integer number (320315707809).

Almost surely, 2^640631415617 is an apocalyptic number.

It is an amenable number.

640631415617 is a deficient number, since it is larger than the sum of its proper divisors (1).

640631415617 is an equidigital number, since it uses as much as digits as its factorization.

640631415617 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 362880, while the sum is 44.

The spelling of 640631415617 in words is "six hundred forty billion, six hundred thirty-one million, four hundred fifteen thousand, six hundred seventeen".