21212020202121 has 48 divisors (see below), whose sum is σ = 35139256222720. Its totient is φ = 12078793651680.

The previous prime is 21212020202089. The next prime is 21212020202141. The reversal of 21212020202121 is 12120202021212.

It is a happy number.

It is not a de Polignac number, because 21212020202121 - 2⁵ = 21212020202089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212020202094 and 21212020202103.

It is not an unprimeable number, because it can be changed into a prime (21212020202141) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 20280690 + ... + 21300948.

Almost surely, 2^{21212020202121} is an apocalyptic number.

21212020202121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21212020202121 is a deficient number, since it is larger than the sum of its proper divisors (13927236020599).

21212020202121 is a wasteful number, since it uses less digits than its factorization.

21212020202121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1021426 (or 1021423 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21212020202121 its reverse (12120202021212), we get a palindrome (33332222223333).

It can be divided in two parts, 2 and 1212020202121, that multiplied together give a palindrome (2424040404242).

The spelling of 21212020202121 in words is "twenty-one trillion, two hundred twelve billion, twenty million, two hundred two thousand, one hundred twenty-one".