21201111111 has 32 divisors (see below), whose sum is σ = 31489795008. Its totient is φ = 12627394560.

The previous prime is 21201111109. The next prime is 21201111131. The reversal of 21201111111 is 11111110212.

It is not a de Polignac number, because 21201111111 - 2¹ = 21201111109 is a prime.

It is a super-2 number, since 2×21201111111² (a number of 21 digits) contains 22 as substring.

21201111111 is a modest number, since divided by 111111 gives 21201 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201111101) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 59650 + ... + 214383.

It is an arithmetic number, because the mean of its divisors is an integer number (984056094).

Almost surely, 2^21201111111 is an apocalyptic number.

21201111111 is a deficient number, since it is larger than the sum of its proper divisors (10288683897).

21201111111 is a wasteful number, since it uses less digits than its factorization.

21201111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274131.

The product of its (nonzero) digits is 4, while the sum is 12.

Adding to 21201111111 its reverse (11111110212), we get a palindrome (32312221323).

The spelling of 21201111111 in words is "twenty-one billion, two hundred one million, one hundred eleven thousand, one hundred eleven".