640308517 has 2 divisors, whose sum is σ = 640308518. Its totient is φ = 640308516.

The previous prime is 640308497. The next prime is 640308547. The reversal of 640308517 is 715803046.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 442934116 + 197374401 = 21046^2 + 14049^2 .

It is a cyclic number.

It is not a de Polignac number, because 640308517 - 2²³ = 631919909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (640308547) 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, 320154258 + 320154259.

It is an arithmetic number, because the mean of its divisors is an integer number (320154259).

Almost surely, 2^640308517 is an apocalyptic number.

It is an amenable number.

640308517 is a deficient number, since it is larger than the sum of its proper divisors (1).

640308517 is an equidigital number, since it uses as much as digits as its factorization.

640308517 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20160, while the sum is 34.

The square root of 640308517 is about 25304.3181492804. The cubic root of 640308517 is about 861.9123287109.

The spelling of 640308517 in words is "six hundred forty million, three hundred eight thousand, five hundred seventeen".