644696 has 16 divisors (see below), whose sum is σ = 1302000. Its totient is φ = 297504.

The previous prime is 644687. The next prime is 644701. The reversal of 644696 is 696446.

644696 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644696.

It is an unprimeable number.

644696 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 3 ways as a sum of consecutive naturals, for example, 2996 + ... + 3203.

It is an arithmetic number, because the mean of its divisors is an integer number (81375).

2⁶⁴⁴⁶⁹⁶ is an apocalyptic number.

It is an amenable number.

644696 is an abundant number, since it is smaller than the sum of its proper divisors (657304).

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

644696 is a wasteful number, since it uses less digits than its factorization.

644696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6218 (or 6214 counting only the distinct ones).

The product of its digits is 31104, while the sum is 35.

The square root of 644696 is about 802.9296357714. The cubic root of 644696 is about 86.3876496979.

It can be divided in two parts, 6446 and 96, that multiplied together give a palindrome (618816).

The spelling of 644696 in words is "six hundred forty-four thousand, six hundred ninety-six".