21000110100021 has 18 divisors (see below), whose sum is σ = 32846326056258. Its totient is φ = 12923144676000.

The previous prime is 21000110099993. The next prime is 21000110100031. The reversal of 21000110100021 is 12000101100012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 672545967921 + 20327564132100 = 820089^2 + 4508610^2 .

It is not a de Polignac number, because 21000110100021 - 2¹⁰ = 21000110098997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21000110099976 and 21000110100012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000110100031) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 6903387730 + ... + 6903390771.

Almost surely, 2^{21000110100021} is an apocalyptic number.

It is an amenable number.

21000110100021 is a deficient number, since it is larger than the sum of its proper divisors (11846215956237).

21000110100021 is a wasteful number, since it uses less digits than its factorization.

21000110100021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13806778533 (or 13806778517 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21000110100021 its reverse (12000101100012), we get a palindrome (33000211200033).

Subtracting from 21000110100021 its reverse (12000101100012), we obtain a palindrome (9000009000009).

The spelling of 21000110100021 in words is "twenty-one trillion, one hundred ten million, one hundred thousand, twenty-one".