645140 has 12 divisors (see below), whose sum is σ = 1354836. Its totient is φ = 258048.

The previous prime is 645137. The next prime is 645149. The reversal of 645140 is 41546.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 198916 + 446224 = 446^2 + 668^2 .

It is a Harshad number since it is a multiple of its sum of digits (20), and also a Moran number because the ratio is a prime number: 32257 = 645140 / (6 + 4 + 5 + 1 + 4 + 0).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645149) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16109 + ... + 16148.

It is an arithmetic number, because the mean of its divisors is an integer number (112903).

2⁶⁴⁵¹⁴⁰ is an apocalyptic number.

It is an amenable number.

645140 is an abundant number, since it is smaller than the sum of its proper divisors (709696).

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

645140 is a wasteful number, since it uses less digits than its factorization.

645140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32266 (or 32264 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 645140 is about 803.2060756742. The cubic root of 645140 is about 86.4074767764.

Adding to 645140 its reverse (41546), we get a palindrome (686686).

The spelling of 645140 in words is "six hundred forty-five thousand, one hundred forty".