21033212221 has 12 divisors (see below), whose sum is σ = 24482245788. Its totient is φ = 18017385792.

The previous prime is 21033212219. The next prime is 21033212251. The reversal of 21033212221 is 12221233012.

It can be written as a sum of positive squares in 2 ways, for example, as 10052268121 + 10980944100 = 100261^2 + 104790^2 .

It is not a de Polignac number, because 21033212221 - 2¹ = 21033212219 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033212251) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50896 + ... + 211321.

It is an arithmetic number, because the mean of its divisors is an integer number (2040187149).

Almost surely, 2^21033212221 is an apocalyptic number.

It is an amenable number.

21033212221 is a deficient number, since it is larger than the sum of its proper divisors (3449033567).

21033212221 is a wasteful number, since it uses less digits than its factorization.

21033212221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263868 (or 263861 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21033212221 its reverse (12221233012), we get a palindrome (33254445233).

The spelling of 21033212221 in words is "twenty-one billion, thirty-three million, two hundred twelve thousand, two hundred twenty-one".