21001111011 has 12 divisors (see below), whose sum is σ = 30386100888. Its totient is φ = 13977127104.

The previous prime is 21001110967. The next prime is 21001111063. The reversal of 21001111011 is 11011110012.

It is not a de Polignac number, because 21001111011 - 2⁷ = 21001110883 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21001110984 and 21001111002.

It is not an unprimeable number, because it can be changed into a prime (21001111081) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1962165 + ... + 1972838.

It is an arithmetic number, because the mean of its divisors is an integer number (2532175074).

Almost surely, 2^21001111011 is an apocalyptic number.

21001111011 is a deficient number, since it is larger than the sum of its proper divisors (9384989877).

21001111011 is a wasteful number, since it uses less digits than its factorization.

21001111011 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3935602 (or 3935599 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 9.

Adding to 21001111011 its reverse (11011110012), we get a palindrome (32012221023).

Subtracting from 21001111011 its reverse (11011110012), we obtain a palindrome (9990000999).

It can be divided in two parts, 2100 and 1111011, that added together give a palindrome (1113111).

The spelling of 21001111011 in words is "twenty-one billion, one million, one hundred eleven thousand, eleven".