645309 has 12 divisors (see below), whose sum is σ = 1065376. Its totient is φ = 368712.

The previous prime is 645257. The next prime is 645313. The reversal of 645309 is 903546.

It is a happy number.

It is not a de Polignac number, because 645309 - 2⁹ = 644797 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 (645329) 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, 5059 + ... + 5184.

2⁶⁴⁵³⁰⁹ is an apocalyptic number.

It is an amenable number.

645309 is a deficient number, since it is larger than the sum of its proper divisors (420067).

645309 is a wasteful number, since it uses less digits than its factorization.

645309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10256 (or 10253 counting only the distinct ones).

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

The square root of 645309 is about 803.3112721729. The cubic root of 645309 is about 86.4150211795.

The spelling of 645309 in words is "six hundred forty-five thousand, three hundred nine".