21000001111221 has 16 divisors (see below), whose sum is σ = 32342247701568. Its totient is φ = 11978610259200.

The previous prime is 21000001111213. The next prime is 21000001111241. The reversal of 21000001111221 is 12211110000012.

It is not a de Polignac number, because 21000001111221 - 2³ = 21000001111213 is a prime.

It is a super-2 number, since 2×21000001111221² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21000001111197 and 21000001111206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000001111211) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18716577970 + ... + 18716579091.

It is an arithmetic number, because the mean of its divisors is an integer number (2021390481348).

Almost surely, 2^{21000001111221} is an apocalyptic number.

It is an amenable number.

21000001111221 is a deficient number, since it is larger than the sum of its proper divisors (11342246590347).

21000001111221 is a wasteful number, since it uses less digits than its factorization.

21000001111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37433157092.

The product of its (nonzero) digits is 8, while the sum is 12.

Adding to 21000001111221 its reverse (12211110000012), we get a palindrome (33211111111233).

The spelling of 21000001111221 in words is "twenty-one trillion, one million, one hundred eleven thousand, two hundred twenty-one".