21210020111 has 4 divisors (see below), whose sum is σ = 24240022992. Its totient is φ = 18180017232.

The previous prime is 21210020053. The next prime is 21210020129. The reversal of 21210020111 is 11102001212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21210020111 - 2²⁶ = 21142911247 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21210020092 and 21210020101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210020141) 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, 1515001430 + ... + 1515001443.

It is an arithmetic number, because the mean of its divisors is an integer number (6060005748).

Almost surely, 2^21210020111 is an apocalyptic number.

21210020111 is a deficient number, since it is larger than the sum of its proper divisors (3030002881).

21210020111 is an equidigital number, since it uses as much as digits as its factorization.

21210020111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3030002880.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21210020111 its reverse (11102001212), we get a palindrome (32312021323).

The spelling of 21210020111 in words is "twenty-one billion, two hundred ten million, twenty thousand, one hundred eleven".