640409513 has 2 divisors, whose sum is σ = 640409514. Its totient is φ = 640409512.

The previous prime is 640409489. The next prime is 640409519. The reversal of 640409513 is 315904046.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 540469504 + 99940009 = 23248^2 + 9997^2 .

It is a cyclic number.

It is not a de Polignac number, because 640409513 - 2⁸ = 640409257 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 640409513.

It is not a weakly prime, because it can be changed into another prime (640409519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320204756 + 320204757.

It is an arithmetic number, because the mean of its divisors is an integer number (320204757).

Almost surely, 2^640409513 is an apocalyptic number.

It is an amenable number.

640409513 is a deficient number, since it is larger than the sum of its proper divisors (1).

640409513 is an equidigital number, since it uses as much as digits as its factorization.

640409513 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 32.

The square root of 640409513 is about 25306.3136983639. The cubic root of 640409513 is about 861.9576428675.

The spelling of 640409513 in words is "six hundred forty million, four hundred nine thousand, five hundred thirteen".