21021021100021 has 4 divisors (see below), whose sum is σ = 21023137817344. Its totient is φ = 21018904382700.

The previous prime is 21021021100007. The next prime is 21021021100033. The reversal of 21021021100021 is 12000112012012.

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 21021021100021 - 2³¹ = 21018873616373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021021099974 and 21021021100010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021021100621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1058343765 + ... + 1058363626.

It is an arithmetic number, because the mean of its divisors is an integer number (5255784454336).

Almost surely, 2^{21021021100021} is an apocalyptic number.

It is an amenable number.

21021021100021 is a deficient number, since it is larger than the sum of its proper divisors (2116717323).

21021021100021 is an equidigital number, since it uses as much as digits as its factorization.

21021021100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2116717322.

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

Adding to 21021021100021 its reverse (12000112012012), we get a palindrome (33021133112033).

The spelling of 21021021100021 in words is "twenty-one trillion, twenty-one billion, twenty-one million, one hundred thousand, twenty-one".