645500 has 24 divisors (see below), whose sum is σ = 1410864. Its totient is φ = 258000.

The previous prime is 645499. The next prime is 645503. The reversal of 645500 is 5546.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645503) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 146 + ... + 1145.

It is an arithmetic number, because the mean of its divisors is an integer number (58786).

645500 is a Friedman number, since it can be written as 500*(6^4-5), using all its digits and the basic arithmetic operations.

2⁶⁴⁵⁵⁰⁰ is an apocalyptic number.

It is an amenable number.

645500 is an abundant number, since it is smaller than the sum of its proper divisors (765364).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645500 is a wasteful number, since it uses less digits than its factorization.

645500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1310 (or 1298 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 20.

The square root of 645500 is about 803.4301463102. The cubic root of 645500 is about 86.4235461088.

The spelling of 645500 in words is "six hundred forty-five thousand, five hundred".