21213244 has 12 divisors (see below), whose sum is σ = 39978904. Its totient is φ = 9790704.

The previous prime is 21213193. The next prime is 21213251. The reversal of 21213244 is 44231212.

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 3 ways as a sum of consecutive naturals, for example, 203922 + ... + 204025.

Almost surely, 2^21213244 is an apocalyptic number.

It is an amenable number.

21213244 is a deficient number, since it is larger than the sum of its proper divisors (18765660).

21213244 is a wasteful number, since it uses less digits than its factorization.

21213244 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407964 (or 407962 counting only the distinct ones).

The product of its digits is 384, while the sum is 19.

The square root of 21213244 is about 4605.7837552365. The cubic root of 21213244 is about 276.8231221009.

Adding to 21213244 its reverse (44231212), we get a palindrome (65444456).

It can be divided in two parts, 212 and 13244, that added together give a square (13456 = 116²).

The spelling of 21213244 in words is "twenty-one million, two hundred thirteen thousand, two hundred forty-four".