640999459 has 2 divisors, whose sum is σ = 640999460. Its totient is φ = 640999458.

The previous prime is 640999439. The next prime is 640999477. The reversal of 640999459 is 954999046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640999459 - 2²⁷ = 506781731 is a prime.

It is not a weakly prime, because it can be changed into another prime (640999439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320499729 + 320499730.

It is an arithmetic number, because the mean of its divisors is an integer number (320499730).

Almost surely, 2^640999459 is an apocalyptic number.

640999459 is a deficient number, since it is larger than the sum of its proper divisors (1).

640999459 is an equidigital number, since it uses as much as digits as its factorization.

640999459 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3149280, while the sum is 55.

The square root of 640999459 is about 25317.9671182344. The cubic root of 640999459 is about 862.2222404346. Note that the first 4 decimals are identical.

The spelling of 640999459 in words is "six hundred forty million, nine hundred ninety-nine thousand, four hundred fifty-nine".