21202123221 has 32 divisors (see below), whose sum is σ = 31758480000. Its totient is φ = 13979009664.

The previous prime is 21202123193. The next prime is 21202123277. The reversal of 21202123221 is 12232120212.

It is not a de Polignac number, because 21202123221 - 2¹⁰ = 21202122197 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21202123194 and 21202123203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202123421) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 926050 + ... + 948668.

It is an arithmetic number, because the mean of its divisors is an integer number (992452500).

Almost surely, 2^21202123221 is an apocalyptic number.

It is an amenable number.

21202123221 is a deficient number, since it is larger than the sum of its proper divisors (10556356779).

21202123221 is a wasteful number, since it uses less digits than its factorization.

21202123221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23010 (or 23004 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21202123221 its reverse (12232120212), we get a palindrome (33434243433).

The spelling of 21202123221 in words is "twenty-one billion, two hundred two million, one hundred twenty-three thousand, two hundred twenty-one".