21001221211021 has 4 divisors (see below), whose sum is σ = 22106548643200. Its totient is φ = 19895893778844.

The previous prime is 21001221211007. The next prime is 21001221211037. The reversal of 21001221211021 is 12011212210012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21001221211021 - 2²⁹ = 21000684340109 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001221210986 and 21001221211004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001221214021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 552663716061 + ... + 552663716098.

It is an arithmetic number, because the mean of its divisors is an integer number (5526637160800).

Almost surely, 2^{21001221211021} is an apocalyptic number.

It is an amenable number.

21001221211021 is a deficient number, since it is larger than the sum of its proper divisors (1105327432179).

21001221211021 is a wasteful number, since it uses less digits than its factorization.

21001221211021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1105327432178.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21001221211021 its reverse (12011212210012), we get a palindrome (33012433421033).

The spelling of 21001221211021 in words is "twenty-one trillion, one billion, two hundred twenty-one million, two hundred eleven thousand, twenty-one".