21222210 has 16 divisors (see below), whose sum is σ = 50933376. Its totient is φ = 5659248.

The previous prime is 21222181. The next prime is 21222211. The reversal of 21222210 is 1222212.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21222211) 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, 353674 + ... + 353733.

It is an arithmetic number, because the mean of its divisors is an integer number (3183336).

Almost surely, 2^21222210 is an apocalyptic number.

21222210 is an abundant number, since it is smaller than the sum of its proper divisors (29711166).

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

21222210 is a wasteful number, since it uses less digits than its factorization.

21222210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 707417.

The product of its (nonzero) digits is 32, while the sum is 12.

The square root of 21222210 is about 4606.7569938081. The cubic root of 21222210 is about 276.8621173392.

Adding to 21222210 its reverse (1222212), we get a palindrome (22444422).

It can be divided in two parts, 212 and 22210, that added together give a palindrome (22422).

The spelling of 21222210 in words is "twenty-one million, two hundred twenty-two thousand, two hundred ten".