21108011 has 4 divisors (see below), whose sum is σ = 21237672. Its totient is φ = 20978352.

The previous prime is 21108007. The next prime is 21108047. The reversal of 21108011 is 11080112.

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 21108011 - 2² = 21108007 is a prime.

It is a super-2 number, since 2×21108011² = 891096256752242, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21108811) 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, 64586 + ... + 64911.

It is an arithmetic number, because the mean of its divisors is an integer number (5309418).

Almost surely, 2^21108011 is an apocalyptic number.

21108011 is a deficient number, since it is larger than the sum of its proper divisors (129661).

21108011 is a wasteful number, since it uses less digits than its factorization.

21108011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129660.

The product of its (nonzero) digits is 16, while the sum is 14.

The square root of 21108011 is about 4594.3455464299. The cubic root of 21108011 is about 276.3646155983.

Adding to 21108011 its reverse (11080112), we get a palindrome (32188123).

The spelling of 21108011 in words is "twenty-one million, one hundred eight thousand, eleven".