644022401 has 16 divisors (see below), whose sum is σ = 728058240. Its totient is φ = 564305280.

The previous prime is 644022389. The next prime is 644022403. The reversal of 644022401 is 104220446.

It is not a de Polignac number, because 644022401 - 2¹⁴ = 644006017 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (644022403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 230525 + ... + 233301.

It is an arithmetic number, because the mean of its divisors is an integer number (45503640).

Almost surely, 2^644022401 is an apocalyptic number.

It is an amenable number.

644022401 is a deficient number, since it is larger than the sum of its proper divisors (84035839).

644022401 is a wasteful number, since it uses less digits than its factorization.

644022401 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3544.

The product of its (nonzero) digits is 1536, while the sum is 23.

The square root of 644022401 is about 25377.5964385913. The cubic root of 644022401 is about 863.5755235345.

Adding to 644022401 its reverse (104220446), we get a palindrome (748242847).

The spelling of 644022401 in words is "six hundred forty-four million, twenty-two thousand, four hundred one".