644269 has 4 divisors (see below), whose sum is σ = 659296. Its totient is φ = 629244.

The previous prime is 644261. The next prime is 644291. The reversal of 644269 is 962446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644269 - 2³ = 644261 is a prime.

It is a super-2 number, since 2×644269² = 830165088722, which contains 22 as substring.

It is a d-powerful number, because it can be written as 6⁵ + 4 + 2¹⁹ + 4⁸ + 6⁶ + 9 .

It is a Duffinian number.

644269 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 644269.

It is a congruent number.

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, 7449 + ... + 7534.

It is an arithmetic number, because the mean of its divisors is an integer number (164824).

2⁶⁴⁴²⁶⁹ is an apocalyptic number.

It is an amenable number.

644269 is a deficient number, since it is larger than the sum of its proper divisors (15027).

644269 is a wasteful number, since it uses less digits than its factorization.

644269 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15026.

The product of its digits is 10368, while the sum is 31.

The square root of 644269 is about 802.6636904707. The cubic root of 644269 is about 86.3685731754.

The spelling of 644269 in words is "six hundred forty-four thousand, two hundred sixty-nine".