645424 has 40 divisors (see below), whose sum is σ = 1406160. Its totient is φ = 284928.

The previous prime is 645419. The next prime is 645431. The reversal of 645424 is 424546.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5979 + ... + 6085.

It is an arithmetic number, because the mean of its divisors is an integer number (35154).

2⁶⁴⁵⁴²⁴ 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 645424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (703080).

645424 is an abundant number, since it is smaller than the sum of its proper divisors (760736).

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

645424 is a wasteful number, since it uses less digits than its factorization.

645424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 151 counting only the distinct ones).

The product of its digits is 3840, while the sum is 25.

The square root of 645424 is about 803.3828477133. The cubic root of 645424 is about 86.4201541918.

It can be divided in two parts, 64542 and 4, that added together give a palindrome (64546).

The spelling of 645424 in words is "six hundred forty-five thousand, four hundred twenty-four".