21222736 has 40 divisors (see below), whose sum is σ = 42611360. Its totient is φ = 10233216.

The previous prime is 21222697. The next prime is 21222739. The reversal of 21222736 is 63722212.

It is a zygodrome in base 4.

It is a self number, because there is not a number n which added to its sum of digits gives 21222736.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222739) 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, 74851 + ... + 75133.

It is an arithmetic number, because the mean of its divisors is an integer number (1065284).

Almost surely, 2^21222736 is an apocalyptic number.

It is an amenable number.

21222736 is an abundant number, since it is smaller than the sum of its proper divisors (21388624).

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

21222736 is a wasteful number, since it uses less digits than its factorization.

21222736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 443 (or 437 counting only the distinct ones).

The product of its digits is 2016, while the sum is 25.

The square root of 21222736 is about 4606.8140835072. The cubic root of 21222736 is about 276.8644046956.

Adding to 21222736 its reverse (63722212), we get a palindrome (84944948).

The spelling of 21222736 in words is "twenty-one million, two hundred twenty-two thousand, seven hundred thirty-six".