644946 has 16 divisors (see below), whose sum is σ = 1365984. Its totient is φ = 202304.

The previous prime is 644933. The next prime is 644951. The reversal of 644946 is 649446.

644946 = T₄ + T₅ + ... + T₁₅₆.

It is an unprimeable number.

644946 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 7 ways as a sum of consecutive naturals, for example, 3060 + ... + 3263.

It is an arithmetic number, because the mean of its divisors is an integer number (85374).

2⁶⁴⁴⁹⁴⁶ is an apocalyptic number.

644946 is an abundant number, since it is smaller than the sum of its proper divisors (721038).

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

644946 is a wasteful number, since it uses less digits than its factorization.

644946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6345.

The product of its digits is 20736, while the sum is 33.

The square root of 644946 is about 803.0853005752. The cubic root of 644946 is about 86.3988147128.

The spelling of 644946 in words is "six hundred forty-four thousand, nine hundred forty-six".