640259 has 2 divisors, whose sum is σ = 640260. Its totient is φ = 640258.

The previous prime is 640249. The next prime is 640261. The reversal of 640259 is 952046.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 640259 - 2¹⁶ = 574723 is a prime.

It is a Sophie Germain prime.

Together with 640261, it forms a pair of twin primes.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640259.

It is not a weakly prime, because it can be changed into another prime (640219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 320129 + 320130.

It is an arithmetic number, because the mean of its divisors is an integer number (320130).

2⁶⁴⁰²⁵⁹ is an apocalyptic number.

640259 is a deficient number, since it is larger than the sum of its proper divisors (1).

640259 is an equidigital number, since it uses as much as digits as its factorization.

640259 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 640259 is about 800.1618586261. The cubic root of 640259 is about 86.1890110040.

The spelling of 640259 in words is "six hundred forty thousand, two hundred fifty-nine".