21200121110021 has 4 divisors (see below), whose sum is σ = 24228709840032. Its totient is φ = 18171532380012.

The previous prime is 21200121109991. The next prime is 21200121110023. The reversal of 21200121110021 is 12001112100212.

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 21200121110021 - 2⁴² = 16802074598917 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21200121109978 and 21200121110005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21200121110023) 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, 1514294364995 + ... + 1514294365008.

It is an arithmetic number, because the mean of its divisors is an integer number (6057177460008).

Almost surely, 2^{21200121110021} is an apocalyptic number.

It is an amenable number.

21200121110021 is a deficient number, since it is larger than the sum of its proper divisors (3028588730011).

21200121110021 is an equidigital number, since it uses as much as digits as its factorization.

21200121110021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3028588730010.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21200121110021 its reverse (12001112100212), we get a palindrome (33201233210233).

The spelling of 21200121110021 in words is "twenty-one trillion, two hundred billion, one hundred twenty-one million, one hundred ten thousand, twenty-one".