21100102012021 has 4 divisors (see below), whose sum is σ = 21176275665772. Its totient is φ = 21023928358272.

The previous prime is 21100102011991. The next prime is 21100102012027. The reversal of 21100102012021 is 12021020100112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6114299689521 + 14985802322500 = 2472711^2 + 3871150^2 .

It is a cyclic number.

It is not a de Polignac number, because 21100102012021 - 2²⁷ = 21099967794293 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21100102011992 and 21100102012010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100102012027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38086826460 + ... + 38086827013.

It is an arithmetic number, because the mean of its divisors is an integer number (5294068916443).

Almost surely, 2^{21100102012021} is an apocalyptic number.

It is an amenable number.

21100102012021 is a deficient number, since it is larger than the sum of its proper divisors (76173653751).

21100102012021 is an equidigital number, since it uses as much as digits as its factorization.

21100102012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76173653750.

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21100102012021 its reverse (12021020100112), we get a palindrome (33121122112133).

The spelling of 21100102012021 in words is "twenty-one trillion, one hundred billion, one hundred two million, twelve thousand, twenty-one".