21211111212021 has 12 divisors (see below), whose sum is σ = 30919356814060. Its totient is φ = 14011009240320.

The previous prime is 21211111212017. The next prime is 21211111212041. The reversal of 21211111212021 is 12021211111212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 16503816875121 + 4707294336900 = 4062489^2 + 2169630^2 .

It is not a de Polignac number, because 21211111212021 - 2² = 21211111212017 is a prime.

It is a super-2 number, since 2×21211111212021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21211111211985 and 21211111212003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211111212001) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10810962940 + ... + 10810964901.

Almost surely, 2^{21211111212021} is an apocalyptic number.

It is an amenable number.

21211111212021 is a deficient number, since it is larger than the sum of its proper divisors (9708245602039).

21211111212021 is a wasteful number, since it uses less digits than its factorization.

21211111212021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21621927956 (or 21621927953 counting only the distinct ones).

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

Adding to 21211111212021 its reverse (12021211111212), we get a palindrome (33232322323233).

The spelling of 21211111212021 in words is "twenty-one trillion, two hundred eleven billion, one hundred eleven million, two hundred twelve thousand, twenty-one".