645188903 has 4 divisors (see below), whose sum is σ = 645378360. Its totient is φ = 644999448.

The previous prime is 645188891. The next prime is 645188953. The reversal of 645188903 is 309881546.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 645188903 - 2¹⁴ = 645172519 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 (645188953) 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, 89525 + ... + 96462.

It is an arithmetic number, because the mean of its divisors is an integer number (161344590).

Almost surely, 2^645188903 is an apocalyptic number.

645188903 is a deficient number, since it is larger than the sum of its proper divisors (189457).

645188903 is a wasteful number, since it uses less digits than its factorization.

645188903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189456.

The product of its (nonzero) digits is 207360, while the sum is 44.

The square root of 645188903 is about 25400.5689503208. The cubic root of 645188903 is about 864.0966001209.

The spelling of 645188903 in words is "six hundred forty-five million, one hundred eighty-eight thousand, nine hundred three".