21000000011 has 4 divisors (see below), whose sum is σ = 21016293000. Its totient is φ = 20983707024.

The previous prime is 20999999981. The next prime is 21000000019. The reversal of 21000000011 is 11000000012.

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 21000000011 - 2¹⁸ = 20999737867 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20999999941 and 21000000004.

It is not an unprimeable number, because it can be changed into a prime (21000000019) 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, 8144561 + ... + 8147138.

It is an arithmetic number, because the mean of its divisors is an integer number (5254073250).

Almost surely, 2^21000000011 is an apocalyptic number.

21000000011 is a deficient number, since it is larger than the sum of its proper divisors (16292989).

21000000011 is a wasteful number, since it uses less digits than its factorization.

21000000011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16292988.

The product of its (nonzero) digits is 2, while the sum is 5.

Adding to 21000000011 its reverse (11000000012), we get a palindrome (32000000023).

Subtracting from 21000000011 its reverse (11000000012), we obtain a palindrome (9999999999).

The spelling of 21000000011 in words is "twenty-one billion, eleven", and thus it is an aban number and an uban number.