645221 has 8 divisors (see below), whose sum is σ = 703200. Its totient is φ = 589680.

The previous prime is 645187. The next prime is 645233. The reversal of 645221 is 122546.

It is a happy number.

645221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 645221 - 2¹⁰ = 644197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 645193 and 645202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35 + ... + 1136.

It is an arithmetic number, because the mean of its divisors is an integer number (87900).

2⁶⁴⁵²²¹ is an apocalyptic number.

It is an amenable number.

645221 is a deficient number, since it is larger than the sum of its proper divisors (57979).

645221 is a wasteful number, since it uses less digits than its factorization.

645221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1219.

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

The square root of 645221 is about 803.2564970170. The cubic root of 645221 is about 86.4110928973.

Adding to 645221 its reverse (122546), we get a palindrome (767767).

The spelling of 645221 in words is "six hundred forty-five thousand, two hundred twenty-one".