21222021 has 8 divisors (see below), whose sum is σ = 28637280. Its totient is φ = 13977392.

The previous prime is 21222013. The next prime is 21222023. The reversal of 21222021 is 12022212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21222021 - 2³ = 21222013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221988 and 21222006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222023) 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, 42366 + ... + 42863.

It is an arithmetic number, because the mean of its divisors is an integer number (3579660).

Almost surely, 2^21222021 is an apocalyptic number.

It is an amenable number.

21222021 is a deficient number, since it is larger than the sum of its proper divisors (7415259).

21222021 is an equidigital number, since it uses as much as digits as its factorization.

21222021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85315.

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

The square root of 21222021 is about 4606.7364804165. The cubic root of 21222021 is about 276.8612954472.

Adding to 21222021 its reverse (12022212), we get a palindrome (33244233).

The spelling of 21222021 in words is "twenty-one million, two hundred twenty-two thousand, twenty-one".