21212744 has 32 divisors (see below), whose sum is σ = 46569600. Its totient is φ = 8868480.

The previous prime is 21212731. The next prime is 21212749. The reversal of 21212744 is 44721212.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21212749) 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 7 ways as a sum of consecutive naturals, for example, 2324 + ... + 6915.

It is an arithmetic number, because the mean of its divisors is an integer number (1455300).

Almost surely, 2^21212744 is an apocalyptic number.

It is an amenable number.

21212744 is an abundant number, since it is smaller than the sum of its proper divisors (25356856).

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

21212744 is a wasteful number, since it uses less digits than its factorization.

21212744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9293 (or 9289 counting only the distinct ones).

The product of its digits is 896, while the sum is 23.

The square root of 21212744 is about 4605.7294753383. The cubic root of 21212744 is about 276.8209471601.

Adding to 21212744 its reverse (44721212), we get a palindrome (65933956).

The spelling of 21212744 in words is "twenty-one million, two hundred twelve thousand, seven hundred forty-four".