644902 has 8 divisors (see below), whose sum is σ = 1000800. Its totient is φ = 311304.

The previous prime is 644899. The next prime is 644909. The reversal of 644902 is 209446.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644909) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 5502 + ... + 5617.

It is an arithmetic number, because the mean of its divisors is an integer number (125100).

2⁶⁴⁴⁹⁰² is an apocalyptic number.

644902 is a deficient number, since it is larger than the sum of its proper divisors (355898).

644902 is a wasteful number, since it uses less digits than its factorization.

644902 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11150.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 644902 is about 803.0579057577. The cubic root of 644902 is about 86.3968498794.

The spelling of 644902 in words is "six hundred forty-four thousand, nine hundred two".