644470 has 24 divisors (see below), whose sum is σ = 1237824. Its totient is φ = 241536.

The previous prime is 644447. The next prime is 644489. The reversal of 644470 is 74446.

It is a happy number.

644470 is nontrivially palindromic in base 4.

It is a congruent number.

It is an unprimeable number.

644470 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2779 + ... + 3001.

It is an arithmetic number, because the mean of its divisors is an integer number (51576).

2⁶⁴⁴⁴⁷⁰ is an apocalyptic number.

644470 is a deficient number, since it is larger than the sum of its proper divisors (593354).

644470 is a wasteful number, since it uses less digits than its factorization.

644470 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 25.

The square root of 644470 is about 802.7888888120. The cubic root of 644470 is about 86.3775540401.

The spelling of 644470 in words is "six hundred forty-four thousand, four hundred seventy".