21000212021221 has 32 divisors (see below), whose sum is σ = 21538411868160. Its totient is φ = 20470326718464.

The previous prime is 21000212021203. The next prime is 21000212021251. The reversal of 21000212021221 is 12212021200012.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21000212021221 - 2¹⁷ = 21000211890149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21000212021195 and 21000212021204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000212021251) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2247690076 + ... + 2247699418.

It is an arithmetic number, because the mean of its divisors is an integer number (673075370880).

Almost surely, 2^{21000212021221} is an apocalyptic number.

It is an amenable number.

21000212021221 is a deficient number, since it is larger than the sum of its proper divisors (538199846939).

21000212021221 is a wasteful number, since it uses less digits than its factorization.

21000212021221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10525.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21000212021221 its reverse (12212021200012), we get a palindrome (33212233221233).

The spelling of 21000212021221 in words is "twenty-one trillion, two hundred twelve million, twenty-one thousand, two hundred twenty-one".