21010021211021 has 4 divisors (see below), whose sum is σ = 21143843002332. Its totient is φ = 20876199419712.

The previous prime is 21010021210993. The next prime is 21010021211027. The reversal of 21010021211021 is 12011212001012.

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 12863620654921 + 8146400556100 = 3586589^2 + 2854190^2 .

It is a cyclic number.

It is not a de Polignac number, because 21010021211021 - 2²⁶ = 21009954102157 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21010021210987 and 21010021211005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010021211027) 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, 66910895420 + ... + 66910895733.

It is an arithmetic number, because the mean of its divisors is an integer number (5285960750583).

Almost surely, 2^{21010021211021} is an apocalyptic number.

It is an amenable number.

21010021211021 is a deficient number, since it is larger than the sum of its proper divisors (133821791311).

21010021211021 is a wasteful number, since it uses less digits than its factorization.

21010021211021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133821791310.

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

Adding to 21010021211021 its reverse (12011212001012), we get a palindrome (33021233212033).

The spelling of 21010021211021 in words is "twenty-one trillion, ten billion, twenty-one million, two hundred eleven thousand, twenty-one".