21011100111 has 8 divisors (see below), whose sum is σ = 31127555760. Its totient is φ = 14007400056.

The previous prime is 21011100079. The next prime is 21011100211. The reversal of 21011100111 is 11100111012.

It is not a de Polignac number, because 21011100111 - 2⁵ = 21011100079 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 = 21011100093 and 21011100102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011100211) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389094420 + ... + 389094473.

It is an arithmetic number, because the mean of its divisors is an integer number (3890944470).

Almost surely, 2^21011100111 is an apocalyptic number.

21011100111 is a deficient number, since it is larger than the sum of its proper divisors (10116455649).

21011100111 is an equidigital number, since it uses as much as digits as its factorization.

21011100111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778188902 (or 778188896 counting only the distinct ones).

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

Adding to 21011100111 its reverse (11100111012), we get a palindrome (32111211123).

It can be divided in two parts, 210111001 and 11, that added together give a palindrome (210111012).

The spelling of 21011100111 in words is "twenty-one billion, eleven million, one hundred thousand, one hundred eleven".