644066 has 8 divisors (see below), whose sum is σ = 970704. Its totient is φ = 320500.

The previous prime is 644057. The next prime is 644089. The reversal of 644066 is 660446.

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

It is an unprimeable 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 3 ways as a sum of consecutive naturals, for example, 140 + ... + 1143.

It is an arithmetic number, because the mean of its divisors is an integer number (121338).

2⁶⁴⁴⁰⁶⁶ is an apocalyptic number.

644066 is a deficient number, since it is larger than the sum of its proper divisors (326638).

644066 is a wasteful number, since it uses less digits than its factorization.

644066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1536.

The product of its (nonzero) digits is 3456, while the sum is 26.

The square root of 644066 is about 802.5372265509. The cubic root of 644066 is about 86.3595010527.

The spelling of 644066 in words is "six hundred forty-four thousand, sixty-six".