21210001100021 has 4 divisors (see below), whose sum is σ = 21230414961600. Its totient is φ = 21189587238444.

The previous prime is 21210001099997. The next prime is 21210001100039. The reversal of 21210001100021 is 12000110001212.

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 21210001100021 - 2²⁶ = 21209933991157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210001099975 and 21210001100011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210001102021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10206929231 + ... + 10206931308.

It is an arithmetic number, because the mean of its divisors is an integer number (5307603740400).

Almost surely, 2^{21210001100021} is an apocalyptic number.

It is an amenable number.

21210001100021 is a deficient number, since it is larger than the sum of its proper divisors (20413861579).

21210001100021 is a wasteful number, since it uses less digits than its factorization.

21210001100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20413861578.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21210001100021 its reverse (12000110001212), we get a palindrome (33210111101233).

The spelling of 21210001100021 in words is "twenty-one trillion, two hundred ten billion, one million, one hundred thousand, twenty-one".