640279 has 2 divisors, whose sum is σ = 640280. Its totient is φ = 640278.

The previous prime is 640267. The next prime is 640303. The reversal of 640279 is 972046.

640279 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 640279 - 2⁵ = 640247 is a prime.

It is a congruent number.

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, 320139 + 320140.

It is an arithmetic number, because the mean of its divisors is an integer number (320140).

2⁶⁴⁰²⁷⁹ is an apocalyptic number.

640279 is a deficient number, since it is larger than the sum of its proper divisors (1).

640279 is an equidigital number, since it uses as much as digits as its factorization.

640279 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 28.

The square root of 640279 is about 800.1743560000. The cubic root of 640279 is about 86.1899084337.

It can be divided in two parts, 640 and 279, that added together give a palindrome (919).

The spelling of 640279 in words is "six hundred forty thousand, two hundred seventy-nine".