640903 has 4 divisors (see below), whose sum is σ = 642880. Its totient is φ = 638928.

The previous prime is 640901. The next prime is 640907. The reversal of 640903 is 309046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 309046 = 2 ⋅154523.

It is a cyclic number.

It is not a de Polignac number, because 640903 - 2¹ = 640901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375 + ... + 1192.

It is an arithmetic number, because the mean of its divisors is an integer number (160720).

2⁶⁴⁰⁹⁰³ is an apocalyptic number.

640903 is a deficient number, since it is larger than the sum of its proper divisors (1977).

640903 is a wasteful number, since it uses less digits than its factorization.

640903 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1976.

The product of its (nonzero) digits is 648, while the sum is 22.

The square root of 640903 is about 800.5641760659. The cubic root of 640903 is about 86.2178988569.

Adding to 640903 its reverse (309046), we get a palindrome (949949).

The spelling of 640903 in words is "six hundred forty thousand, nine hundred three".