645420 has 48 divisors (see below), whose sum is σ = 1870848. Its totient is φ = 166080.

The previous prime is 645419. The next prime is 645431. The reversal of 645420 is 24546.

645420 = 107² + 108² + ... + 146².

It is a happy number.

645420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1687 + ... + 2033.

It is an arithmetic number, because the mean of its divisors is an integer number (38976).

2⁶⁴⁵⁴²⁰ is an apocalyptic number.

645420 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (935424).

645420 is an abundant number, since it is smaller than the sum of its proper divisors (1225428).

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

645420 is a wasteful number, since it uses less digits than its factorization.

645420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 390 (or 388 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 645420 is about 803.3803582364. The cubic root of 645420 is about 86.4199756625.

Adding to 645420 its reverse (24546), we get a palindrome (669966).

The spelling of 645420 in words is "six hundred forty-five thousand, four hundred twenty".