21001109111 has 2 divisors, whose sum is σ = 21001109112. Its totient is φ = 21001109110.

The previous prime is 21001109081. The next prime is 21001109119. The reversal of 21001109111 is 11190110012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21001109111 - 2³⁰ = 19927367287 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21001109111.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001109119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500554555 + 10500554556.

It is an arithmetic number, because the mean of its divisors is an integer number (10500554556).

Almost surely, 2^21001109111 is an apocalyptic number.

21001109111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001109111 is an equidigital number, since it uses as much as digits as its factorization.

21001109111 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 17.

Adding to 21001109111 its reverse (11190110012), we get a palindrome (32191219123).

The spelling of 21001109111 in words is "twenty-one billion, one million, one hundred nine thousand, one hundred eleven".