21244764 has 48 divisors (see below), whose sum is σ = 52835328. Its totient is φ = 6620928.

The previous prime is 21244757. The next prime is 21244777. The reversal of 21244764 is 46744212.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 45259 + ... + 45725.

It is an arithmetic number, because the mean of its divisors is an integer number (1100736).

Almost surely, 2^21244764 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21244764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26417664).

21244764 is an abundant number, since it is smaller than the sum of its proper divisors (31590564).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21244764 is a wasteful number, since it uses less digits than its factorization.

21244764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 714 (or 712 counting only the distinct ones).

The product of its digits is 10752, while the sum is 30.

The square root of 21244764 is about 4609.2042697194. The cubic root of 21244764 is about 276.9601614391.

Adding to 21244764 its reverse (46744212), we get a palindrome (67988976).

The spelling of 21244764 in words is "twenty-one million, two hundred forty-four thousand, seven hundred sixty-four".