640409713 has 2 divisors, whose sum is σ = 640409714. Its totient is φ = 640409712.

The previous prime is 640409699. The next prime is 640409741. The reversal of 640409713 is 317904046.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 347897104 + 292512609 = 18652^2 + 17103^2 .

It is a cyclic number.

It is not a de Polignac number, because 640409713 - 2⁵ = 640409681 is a prime.

It is a super-3 number, since 3×640409713³ (a number of 27 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (640409753) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320204856 + 320204857.

It is an arithmetic number, because the mean of its divisors is an integer number (320204857).

Almost surely, 2^640409713 is an apocalyptic number.

It is an amenable number.

640409713 is a deficient number, since it is larger than the sum of its proper divisors (1).

640409713 is an equidigital number, since it uses as much as digits as its factorization.

640409713 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 640409713 is about 25306.3176499466. The cubic root of 640409713 is about 861.9577325973.

The spelling of 640409713 in words is "six hundred forty million, four hundred nine thousand, seven hundred thirteen".