644222 has 4 divisors (see below), whose sum is σ = 966336. Its totient is φ = 322110.

The previous prime is 644201. The next prime is 644227. The reversal of 644222 is 222446.

It is a semiprime because it is the product of two primes.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 644194 and 644203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161054 + ... + 161057.

It is an arithmetic number, because the mean of its divisors is an integer number (241584).

2⁶⁴⁴²²² is an apocalyptic number.

644222 is a deficient number, since it is larger than the sum of its proper divisors (322114).

644222 is a wasteful number, since it uses less digits than its factorization.

644222 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322113.

The product of its digits is 768, while the sum is 20.

The square root of 644222 is about 802.6344124195. The cubic root of 644222 is about 86.3664729027.

Adding to 644222 its reverse (222446), we get a palindrome (866668).

The spelling of 644222 in words is "six hundred forty-four thousand, two hundred twenty-two".