21111020011 has 4 divisors (see below), whose sum is σ = 21111391192. Its totient is φ = 21110648832.

The previous prime is 21111020009. The next prime is 21111020039. The reversal of 21111020011 is 11002011112.

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 21111020011 - 2¹ = 21111020009 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21111020011.

It is not an unprimeable number, because it can be changed into a prime (21111020111) 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, 80406 + ... + 220651.

It is an arithmetic number, because the mean of its divisors is an integer number (5277847798).

Almost surely, 2^21111020011 is an apocalyptic number.

21111020011 is a deficient number, since it is larger than the sum of its proper divisors (371181).

21111020011 is an equidigital number, since it uses as much as digits as its factorization.

21111020011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371180.

The product of its (nonzero) digits is 4, while the sum is 10.

Adding to 21111020011 its reverse (11002011112), we get a palindrome (32113031123).

The spelling of 21111020011 in words is "twenty-one billion, one hundred eleven million, twenty thousand, eleven".