644217 has 8 divisors (see below), whose sum is σ = 981696. Its totient is φ = 368112.

The previous prime is 644201. The next prime is 644227. The reversal of 644217 is 712446.

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

It is not a de Polignac number, because 644217 - 2⁴ = 644201 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644217.

It is not an unprimeable number, because it can be changed into a prime (644227) 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 7 ways as a sum of consecutive naturals, for example, 15318 + ... + 15359.

It is an arithmetic number, because the mean of its divisors is an integer number (122712).

2⁶⁴⁴²¹⁷ is an apocalyptic number.

It is an amenable number.

644217 is a deficient number, since it is larger than the sum of its proper divisors (337479).

644217 is a wasteful number, since it uses less digits than its factorization.

644217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30687.

The product of its digits is 1344, while the sum is 24.

The square root of 644217 is about 802.6312976704. The cubic root of 644217 is about 86.3662494635.

It can be divided in two parts, 644 and 217, that added together give a triangular number (861 = T₄₁).

The spelling of 644217 in words is "six hundred forty-four thousand, two hundred seventeen".