644398 has 16 divisors (see below), whose sum is σ = 1013760. Its totient is φ = 306936.

The previous prime is 644383. The next prime is 644401. The reversal of 644398 is 893446.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 5011 + ... + 5137.

It is an arithmetic number, because the mean of its divisors is an integer number (63360).

2⁶⁴⁴³⁹⁸ is an apocalyptic number.

644398 is the 508-th heptagonal number.

644398 is a deficient number, since it is larger than the sum of its proper divisors (369362).

644398 is a wasteful number, since it uses less digits than its factorization.

644398 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 231.

The product of its digits is 20736, while the sum is 34.

The square root of 644398 is about 802.7440438895. The cubic root of 644398 is about 86.3743372286.

The spelling of 644398 in words is "six hundred forty-four thousand, three hundred ninety-eight".