21102111010021 has 4 divisors (see below), whose sum is σ = 21145088833344. Its totient is φ = 21059133186700.

The previous prime is 21102111009913. The next prime is 21102111010037. The reversal of 21102111010021 is 12001011120112.

It is a happy number.

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 21102111010021 - 2¹⁵ = 21102110977253 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21102111009983 and 21102111010010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21102111010061) 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, 21488910925 + ... + 21488911906.

It is an arithmetic number, because the mean of its divisors is an integer number (5286272208336).

Almost surely, 2^{21102111010021} is an apocalyptic number.

It is an amenable number.

21102111010021 is a deficient number, since it is larger than the sum of its proper divisors (42977823323).

21102111010021 is an equidigital number, since it uses as much as digits as its factorization.

21102111010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42977823322.

The product of its (nonzero) digits is 8, while the sum is 13.

Adding to 21102111010021 its reverse (12001011120112), we get a palindrome (33103122130133).

The spelling of 21102111010021 in words is "twenty-one trillion, one hundred two billion, one hundred eleven million, ten thousand, twenty-one".