644026469 has 4 divisors (see below), whose sum is σ = 646699020. Its totient is φ = 641353920.

The previous prime is 644026459. The next prime is 644026499. The reversal of 644026469 is 964620446.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 559937569 + 84088900 = 23663^2 + 9170^2 .

It is a cyclic number.

It is not a de Polignac number, because 644026469 - 2²⁴ = 627249253 is a prime.

It is a super-2 number, since 2×644026469² = 829540185545215922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644026459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1335914 + ... + 1336395.

It is an arithmetic number, because the mean of its divisors is an integer number (161674755).

Almost surely, 2^644026469 is an apocalyptic number.

It is an amenable number.

644026469 is a deficient number, since it is larger than the sum of its proper divisors (2672551).

644026469 is a wasteful number, since it uses less digits than its factorization.

644026469 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2672550.

The product of its (nonzero) digits is 248832, while the sum is 41.

The square root of 644026469 is about 25377.6765878991. The cubic root of 644026469 is about 863.5773418035.

The spelling of 644026469 in words is "six hundred forty-four million, twenty-six thousand, four hundred sixty-nine".