645380 has 36 divisors (see below), whose sum is σ = 1440012. Its totient is φ = 242880.

The previous prime is 645367. The next prime is 645383. The reversal of 645380 is 83546.

It can be written as a sum of positive squares in 2 ways, for example, as 103684 + 541696 = 322^2 + 736^2 .

It is a Smith number, since the sum of its digits (26) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (645383) by changing a digit.

645380 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 11 ways as a sum of consecutive naturals, for example, 10550 + ... + 10610.

2⁶⁴⁵³⁸⁰ 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 645380, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (720006).

645380 is an abundant number, since it is smaller than the sum of its proper divisors (794632).

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

645380 is a wasteful number, since it uses less digits than its factorization.

645380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 645380 is about 803.3554630424. The cubic root of 645380 is about 86.4181903287.

The spelling of 645380 in words is "six hundred forty-five thousand, three hundred eighty".