640357 has 4 divisors (see below), whose sum is σ = 674080. Its totient is φ = 606636.

The previous prime is 640333. The next prime is 640363. The reversal of 640357 is 753046.

640357 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 640357 - 2⁷ = 640229 is a prime.

It is a Duffinian number.

640357 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640307) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16833 + ... + 16870.

It is an arithmetic number, because the mean of its divisors is an integer number (168520).

2⁶⁴⁰³⁵⁷ is an apocalyptic number.

It is an amenable number.

640357 is a deficient number, since it is larger than the sum of its proper divisors (33723).

640357 is a wasteful number, since it uses less digits than its factorization.

640357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33722.

The product of its (nonzero) digits is 2520, while the sum is 25.

The square root of 640357 is about 800.2230938932. The cubic root of 640357 is about 86.1934082308.

The spelling of 640357 in words is "six hundred forty thousand, three hundred fifty-seven".