21212422 has 16 divisors (see below), whose sum is σ = 39670272. Its totient is φ = 8264520.

The previous prime is 21212353. The next prime is 21212423. The reversal of 21212422 is 22421212.

It is a junction number, because it is equal to n+sod(n) for n = 21212396 and 21212405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212423) 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, 68718 + ... + 69025.

It is an arithmetic number, because the mean of its divisors is an integer number (2479392).

Almost surely, 2^21212422 is an apocalyptic number.

21212422 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21212422 is a deficient number, since it is larger than the sum of its proper divisors (18457850).

21212422 is a wasteful number, since it uses less digits than its factorization.

21212422 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137763.

The product of its digits is 128, while the sum is 16.

The square root of 21212422 is about 4605.6945187452. The cubic root of 21212422 is about 276.8195464802.

Adding to 21212422 its reverse (22421212), we get a palindrome (43633634).

The spelling of 21212422 in words is "twenty-one million, two hundred twelve thousand, four hundred twenty-two".