21111888 has 80 divisors (see below), whose sum is σ = 65630720. Its totient is φ = 5712768.

The previous prime is 21111877. The next prime is 21111931. The reversal of 21111888 is 88811112.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4731 + ... + 8037.

It is an arithmetic number, because the mean of its divisors is an integer number (820384).

Almost surely, 2^21111888 is an apocalyptic number.

21111888 is a gapful number since it is divisible by the number (28) 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 21111888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32815360).

21111888 is an abundant number, since it is smaller than the sum of its proper divisors (44518832).

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

21111888 is a wasteful number, since it uses less digits than its factorization.

21111888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3344 (or 3338 counting only the distinct ones).

The product of its digits is 1024, while the sum is 30.

The square root of 21111888 is about 4594.7674587513. The cubic root of 21111888 is about 276.3815349253.

The spelling of 21111888 in words is "twenty-one million, one hundred eleven thousand, eight hundred eighty-eight".