21201011111 has 8 divisors (see below), whose sum is σ = 24285947904. Its totient is φ = 18130129560.

The previous prime is 21201011087. The next prime is 21201011141. The reversal of 21201011111 is 11111010212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21201011111 - 2²² = 21196816807 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201011092 and 21201011101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201011141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3510575 + ... + 3516608.

It is an arithmetic number, because the mean of its divisors is an integer number (3035743488).

Almost surely, 2^21201011111 is an apocalyptic number.

21201011111 is a deficient number, since it is larger than the sum of its proper divisors (3084936793).

21201011111 is an equidigital number, since it uses as much as digits as its factorization.

21201011111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7027621.

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

Adding to 21201011111 its reverse (11111010212), we get a palindrome (32312021323).

It can be divided in two parts, 2120101 and 1111, that added together give a palindrome (2121212).

The spelling of 21201011111 in words is "twenty-one billion, two hundred one million, eleven thousand, one hundred eleven".