21101312221 has 24 divisors (see below), whose sum is σ = 23930569152. Its totient is φ = 18451497600.

The previous prime is 21101312207. The next prime is 21101312233. The reversal of 21101312221 is 12221310112.

It is not a de Polignac number, because 21101312221 - 2¹⁵ = 21101279453 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101312195 and 21101312204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101316221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1759381 + ... + 1771333.

It is an arithmetic number, because the mean of its divisors is an integer number (997107048).

Almost surely, 2^21101312221 is an apocalyptic number.

It is an amenable number.

21101312221 is a deficient number, since it is larger than the sum of its proper divisors (2829256931).

21101312221 is a wasteful number, since it uses less digits than its factorization.

21101312221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12193 (or 12162 counting only the distinct ones).

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21101312221 its reverse (12221310112), we get a palindrome (33322622333).

The spelling of 21101312221 in words is "twenty-one billion, one hundred one million, three hundred twelve thousand, two hundred twenty-one".