640409699 has 2 divisors, whose sum is σ = 640409700. Its totient is φ = 640409698.

The previous prime is 640409681. The next prime is 640409713. The reversal of 640409699 is 996904046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640409699 - 2⁸ = 640409443 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (640409899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320204849 + 320204850.

It is an arithmetic number, because the mean of its divisors is an integer number (320204850).

Almost surely, 2^640409699 is an apocalyptic number.

640409699 is a deficient number, since it is larger than the sum of its proper divisors (1).

640409699 is an equidigital number, since it uses as much as digits as its factorization.

640409699 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 419904, while the sum is 47.

The square root of 640409699 is about 25306.3173733359. The cubic root of 640409699 is about 861.9577263162.

The spelling of 640409699 in words is "six hundred forty million, four hundred nine thousand, six hundred ninety-nine".