21021110111021 has 4 divisors (see below), whose sum is σ = 21021182379132. Its totient is φ = 21021037842912.

The previous prime is 21021110111003. The next prime is 21021110111047. The reversal of 21021110111021 is 12011101112012.

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 10438359414025 + 10582750696996 = 3230845^2 + 3253114^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21021110111021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21021110110987 and 21021110111005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021110111051) 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, 35695970 + ... + 36280083.

It is an arithmetic number, because the mean of its divisors is an integer number (5255295594783).

Almost surely, 2^{21021110111021} is an apocalyptic number.

It is an amenable number.

21021110111021 is a deficient number, since it is larger than the sum of its proper divisors (72268111).

21021110111021 is an equidigital number, since it uses as much as digits as its factorization.

21021110111021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72268110.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21021110111021 its reverse (12011101112012), we get a palindrome (33032211223033).

The spelling of 21021110111021 in words is "twenty-one trillion, twenty-one billion, one hundred ten million, one hundred eleven thousand, twenty-one".