21122225221 has 4 divisors (see below), whose sum is σ = 21122844652. Its totient is φ = 21121605792.

The previous prime is 21122225183. The next prime is 21122225227. The reversal of 21122225221 is 12252222112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11687988321 + 9434236900 = 108111^2 + 97130^2 .

It is a cyclic number.

It is not a de Polignac number, because 21122225221 - 2¹⁹ = 21121700933 is a prime.

It is a super-2 number, since 2×21122225221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21122225192 and 21122225201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21122225227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 255390 + ... + 327823.

It is an arithmetic number, because the mean of its divisors is an integer number (5280711163).

Almost surely, 2^21122225221 is an apocalyptic number.

It is an amenable number.

21122225221 is a deficient number, since it is larger than the sum of its proper divisors (619431).

21122225221 is an equidigital number, since it uses as much as digits as its factorization.

21122225221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 619430.

The product of its digits is 640, while the sum is 22.

Adding to 21122225221 its reverse (12252222112), we get a palindrome (33374447333).

The spelling of 21122225221 in words is "twenty-one billion, one hundred twenty-two million, two hundred twenty-five thousand, two hundred twenty-one".