645624 has 96 divisors (see below), whose sum is σ = 2120400. Its totient is φ = 181440.

The previous prime is 645611. The next prime is 645629. The reversal of 645624 is 426546.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

Its product of digits (5760) is a multiple of the sum of its prime factors (90).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645629) by changing a digit.

645624 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10554 + ... + 10614.

2⁶⁴⁵⁶²⁴ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1060200).

645624 is an abundant number, since it is smaller than the sum of its proper divisors (1474776).

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

645624 is a wasteful number, since it uses less digits than its factorization.

645624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90 (or 73 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 645624 is about 803.5073117278. The cubic root of 645624 is about 86.4290797177.

The spelling of 645624 in words is "six hundred forty-five thousand, six hundred twenty-four".