220644 has 36 divisors (see below), whose sum is σ = 580944. Its totient is φ = 73224.

The previous prime is 220613. The next prime is 220663. The reversal of 220644 is 446022.

220644 is a `hidden beast` number, since 2 + 20 + 644 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an Ulam number.

It is a plaindrome in base 15.

It is an unprimeable number.

220644 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 859 + ... + 1085.

2²²⁰⁶⁴⁴ 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 220644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (290472).

220644 is an abundant number, since it is smaller than the sum of its proper divisors (360300).

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

220644 is a wasteful number, since it uses less digits than its factorization.

220644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 246 (or 232 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 220644 is about 469.7275806252. The cubic root of 220644 is about 60.4269546227.

Adding to 220644 its reverse (446022), we get a palindrome (666666).

The spelling of 220644 in words is "two hundred twenty thousand, six hundred forty-four".