645220 has 12 divisors (see below), whose sum is σ = 1355004. Its totient is φ = 258080.

The previous prime is 645187. The next prime is 645233. The reversal of 645220 is 22546.

It can be written as a sum of positive squares in 2 ways, for example, as 135424 + 509796 = 368^2 + 714^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16111 + ... + 16150.

It is an arithmetic number, because the mean of its divisors is an integer number (112917).

2⁶⁴⁵²²⁰ is an apocalyptic number.

It is an amenable number.

645220 is an abundant number, since it is smaller than the sum of its proper divisors (709784).

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

645220 is a wasteful number, since it uses less digits than its factorization.

645220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32270 (or 32268 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 19.

The square root of 645220 is about 803.2558745506. The cubic root of 645220 is about 86.4110482557.

Adding to 645220 its reverse (22546), we get a palindrome (667766).

The spelling of 645220 in words is "six hundred forty-five thousand, two hundred twenty".