21111116205 has 48 divisors (see below), whose sum is σ = 35915463360. Its totient is φ = 10586953728.

The previous prime is 21111116183. The next prime is 21111116209. The reversal of 21111116205 is 50261111112.

It is not a de Polignac number, because 21111116205 - 2³¹ = 18963632557 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111116209) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7181626 + ... + 7184564.

It is an arithmetic number, because the mean of its divisors is an integer number (748238820).

Almost surely, 2^21111116205 is an apocalyptic number.

It is an amenable number.

21111116205 is a deficient number, since it is larger than the sum of its proper divisors (14804347155).

21111116205 is a wasteful number, since it uses less digits than its factorization.

21111116205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4638 (or 4621 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 21.

Adding to 21111116205 its reverse (50261111112), we get a palindrome (71372227317).

The spelling of 21111116205 in words is "twenty-one billion, one hundred eleven million, one hundred sixteen thousand, two hundred five".