640403 has 4 divisors (see below), whose sum is σ = 644640. Its totient is φ = 636168.

The previous prime is 640369. The next prime is 640411. The reversal of 640403 is 304046.

640403 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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640403 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640403.

It is not an unprimeable number, because it can be changed into a prime (640463) 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, 1883 + ... + 2196.

It is an arithmetic number, because the mean of its divisors is an integer number (161160).

2⁶⁴⁰⁴⁰³ is an apocalyptic number.

640403 is a deficient number, since it is larger than the sum of its proper divisors (4237).

640403 is a wasteful number, since it uses less digits than its factorization.

640403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4236.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 640403 is about 800.2518353618. The cubic root of 640403 is about 86.1954720805.

Adding to 640403 its reverse (304046), we get a palindrome (944449).

The spelling of 640403 in words is "six hundred forty thousand, four hundred three".