21212222 has 16 divisors (see below), whose sum is σ = 32372352. Its totient is φ = 10423200.

The previous prime is 21212197. The next prime is 21212239. The reversal of 21212222 is 22221212.

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

It is a junction number, because it is equal to n+sod(n) for n = 21212197 and 21212206.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 34643 + ... + 35249.

It is an arithmetic number, because the mean of its divisors is an integer number (2023272).

Almost surely, 2^21212222 is an apocalyptic number.

21212222 is a deficient number, since it is larger than the sum of its proper divisors (11160130).

21212222 is a wasteful number, since it uses less digits than its factorization.

21212222 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 883.

The product of its digits is 64, while the sum is 14.

The square root of 21212222 is about 4605.6728064421. The cubic root of 21212222 is about 276.8186764855.

Adding to 21212222 its reverse (22221212), we get a palindrome (43433434).

The spelling of 21212222 in words is "twenty-one million, two hundred twelve thousand, two hundred twenty-two".