21111100 has 36 divisors (see below), whose sum is σ = 46262664. Its totient is φ = 8361280.

The previous prime is 21111073. The next prime is 21111113. The reversal of 21111100 is 111112.

It is a nialpdrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9714 + ... + 11686.

It is an arithmetic number, because the mean of its divisors is an integer number (1285074).

Almost surely, 2^21111100 is an apocalyptic number.

21111100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21111100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23131332).

21111100 is an abundant number, since it is smaller than the sum of its proper divisors (25151564).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21111100 is a wasteful number, since it uses less digits than its factorization.

21111100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2094 (or 2087 counting only the distinct ones).

The product of its (nonzero) digits is 2, while the sum is 7.

The square root of 21111100 is about 4594.6817082362. The cubic root of 21111100 is about 276.3780962409.

Adding to 21111100 its reverse (111112), we get a palindrome (21222212).

It can be divided in two parts, 211 and 11100, that added together give a palindrome (11311).

The spelling of 21111100 in words is "twenty-one million, one hundred eleven thousand, one hundred".