644267 has 4 divisors (see below), whose sum is σ = 693840. Its totient is φ = 594696.

The previous prime is 644261. The next prime is 644291. The reversal of 644267 is 762446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 762446 = 2 ⋅381223.

It is a cyclic number.

It is not a de Polignac number, because 644267 - 2¹⁰ = 643243 is a prime.

It is a d-powerful number, because it can be written as 6⁵ + 4 + 2¹⁹ + 4⁸ + 6⁶ + 7 .

It is a Duffinian number.

It is a nialpdrome in base 7.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644267.

It is not an unprimeable number, because it can be changed into a prime (644261) 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, 24767 + ... + 24792.

It is an arithmetic number, because the mean of its divisors is an integer number (173460).

2⁶⁴⁴²⁶⁷ is an apocalyptic number.

644267 is a deficient number, since it is larger than the sum of its proper divisors (49573).

644267 is a wasteful number, since it uses less digits than its factorization.

644267 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49572.

The product of its digits is 8064, while the sum is 29.

The square root of 644267 is about 802.6624446179. The cubic root of 644267 is about 86.3684838041.

The spelling of 644267 in words is "six hundred forty-four thousand, two hundred sixty-seven".