21110111205 has 64 divisors (see below), whose sum is σ = 35326368000. Its totient is φ = 10756841472.

The previous prime is 21110111203. The next prime is 21110111207. The reversal of 21110111205 is 50211101112.

It is an interprime number because it is at equal distance from previous prime (21110111203) and next prime (21110111207).

It is not a de Polignac number, because 21110111205 - 2¹ = 21110111203 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110111203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5110581 + ... + 5114709.

It is an arithmetic number, because the mean of its divisors is an integer number (551974500).

Almost surely, 2^21110111205 is an apocalyptic number.

It is an amenable number.

21110111205 is a deficient number, since it is larger than the sum of its proper divisors (14216256795).

21110111205 is a wasteful number, since it uses less digits than its factorization.

21110111205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4358.

The product of its (nonzero) digits is 20, while the sum is 15.

Adding to 21110111205 its reverse (50211101112), we get a palindrome (71321212317).

The spelling of 21110111205 in words is "twenty-one billion, one hundred ten million, one hundred eleven thousand, two hundred five".