21003311111 has 2 divisors, whose sum is σ = 21003311112. Its totient is φ = 21003311110.

The previous prime is 21003311071. The next prime is 21003311129. The reversal of 21003311111 is 11111330012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21003311111 is a prime.

It is a super-2 number, since 2×21003311111² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21003371111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501655555 + 10501655556.

It is an arithmetic number, because the mean of its divisors is an integer number (10501655556).

Almost surely, 2^21003311111 is an apocalyptic number.

21003311111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003311111 is an equidigital number, since it uses as much as digits as its factorization.

21003311111 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18, while the sum is 14.

Adding to 21003311111 its reverse (11111330012), we get a palindrome (32114641123).

The spelling of 21003311111 in words is "twenty-one billion, three million, three hundred eleven thousand, one hundred eleven".