21101021111 has 4 divisors (see below), whose sum is σ = 21102218424. Its totient is φ = 21099823800.

The previous prime is 21101021047. The next prime is 21101021147. The reversal of 21101021111 is 11112010112.

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 21101021111 - 2⁶ = 21101021047 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21101021092 and 21101021101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21104021111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 571820 + ... + 607601.

It is an arithmetic number, because the mean of its divisors is an integer number (5275554606).

Almost surely, 2^21101021111 is an apocalyptic number.

21101021111 is a deficient number, since it is larger than the sum of its proper divisors (1197313).

21101021111 is a wasteful number, since it uses less digits than its factorization.

21101021111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1197312.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21101021111 its reverse (11112010112), we get a palindrome (32213031223).

The spelling of 21101021111 in words is "twenty-one billion, one hundred one million, twenty-one thousand, one hundred eleven".