21221211111021 has 24 divisors (see below), whose sum is σ = 30740929160760. Its totient is φ = 14106830217216.

The previous prime is 21221211111017. The next prime is 21221211111029. The reversal of 21221211111021 is 12011111212212.

It is a happy number.

21221211111021 is a `hidden beast` number, since 212 + 212 + 111 + 110 + 21 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 7818253500996 + 13402957610025 = 2796114^2 + 3661005^2 .

It is not a de Polignac number, because 21221211111021 - 2² = 21221211111017 is a prime.

It is a super-2 number, since 2×21221211111021² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21221211110985 and 21221211111003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221211111029) 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, 88229095 + ... + 88469291.

It is an arithmetic number, because the mean of its divisors is an integer number (1280872048365).

Almost surely, 2^{21221211111021} is an apocalyptic number.

It is an amenable number.

21221211111021 is a deficient number, since it is larger than the sum of its proper divisors (9519718049739).

21221211111021 is a wasteful number, since it uses less digits than its factorization.

21221211111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268365 (or 268362 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 18.

Adding to 21221211111021 its reverse (12011111212212), we get a palindrome (33232322323233).

The spelling of 21221211111021 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred eleven million, one hundred eleven thousand, twenty-one".