645903 has 12 divisors (see below), whose sum is σ = 955240. Its totient is φ = 420336.

The previous prime is 645901. The next prime is 645907. The reversal of 645903 is 309546.

It is a happy number.

It is not a de Polignac number, because 645903 - 2¹ = 645901 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645903.

It is not an unprimeable number, because it can be changed into a prime (645901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 448 + ... + 1221.

2⁶⁴⁵⁹⁰³ is an apocalyptic number.

645903 is a deficient number, since it is larger than the sum of its proper divisors (309337).

645903 is a wasteful number, since it uses less digits than its factorization.

645903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1718 (or 1715 counting only the distinct ones).

The product of its (nonzero) digits is 3240, while the sum is 27.

The square root of 645903 is about 803.6809068281. The cubic root of 645903 is about 86.4415277476.

The spelling of 645903 in words is "six hundred forty-five thousand, nine hundred three".