21111011 has 4 divisors (see below), whose sum is σ = 21304800. Its totient is φ = 20917224.

The previous prime is 21111007. The next prime is 21111029. The reversal of 21111011 is 11011112.

It is a happy number.

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 21111011 - 2² = 21111007 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 21111011.

It is not an unprimeable number, because it can be changed into a prime (21111061) 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, 96731 + ... + 96948.

It is an arithmetic number, because the mean of its divisors is an integer number (5326200).

Almost surely, 2^21111011 is an apocalyptic number.

21111011 is a deficient number, since it is larger than the sum of its proper divisors (193789).

21111011 is a wasteful number, since it uses less digits than its factorization.

21111011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193788.

The product of its (nonzero) digits is 2, while the sum is 8.

The square root of 21111011 is about 4594.6720231155. The cubic root of 21111011 is about 276.3777078562.

Adding to 21111011 its reverse (11011112), we get a palindrome (32122123).

The spelling of 21111011 in words is "twenty-one million, one hundred eleven thousand, eleven".