21744164 has 12 divisors (see below), whose sum is σ = 40979484. Its totient is φ = 10035744.

The previous prime is 21744161. The next prime is 21744167. The reversal of 21744164 is 46144712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21744161) and next prime (21744167).

It can be written as a sum of positive squares in 2 ways, for example, as 14137600 + 7606564 = 3760^2 + 2758^2 .

It is not an unprimeable number, because it can be changed into a prime (21744161) 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, 209027 + ... + 209130.

It is an arithmetic number, because the mean of its divisors is an integer number (3414957).

Almost surely, 2^21744164 is an apocalyptic number.

It is an amenable number.

21744164 is a deficient number, since it is larger than the sum of its proper divisors (19235320).

21744164 is a wasteful number, since it uses less digits than its factorization.

21744164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418174 (or 418172 counting only the distinct ones).

The product of its digits is 5376, while the sum is 29.

The square root of 21744164 is about 4663.0637996922. The cubic root of 21744164 is about 279.1135400303.

Adding to 21744164 its reverse (46144712), we get a palindrome (67888876).

The spelling of 21744164 in words is "twenty-one million, seven hundred forty-four thousand, one hundred sixty-four".