21210122221 has 24 divisors (see below), whose sum is σ = 22940669696. Its totient is φ = 19588029120.

The previous prime is 21210122207. The next prime is 21210122231. The reversal of 21210122221 is 12222101212.

It is a happy number.

It is not a de Polignac number, because 21210122221 - 2²³ = 21201733613 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210122195 and 21210122204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210122201) 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 23 ways as a sum of consecutive naturals, for example, 8575441 + ... + 8577913.

Almost surely, 2^21210122221 is an apocalyptic number.

It is an amenable number.

21210122221 is a deficient number, since it is larger than the sum of its proper divisors (1730547475).

21210122221 is a wasteful number, since it uses less digits than its factorization.

21210122221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3073 (or 3050 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21210122221 its reverse (12222101212), we get a palindrome (33432223433).

The spelling of 21210122221 in words is "twenty-one billion, two hundred ten million, one hundred twenty-two thousand, two hundred twenty-one".