21111424 has 64 divisors (see below), whose sum is σ = 44945280. Its totient is φ = 9856000.

The previous prime is 21111397. The next prime is 21111457. The reversal of 21111424 is 42411112.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21111398 and 21111407.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 208974 + ... + 209074.

It is an arithmetic number, because the mean of its divisors is an integer number (702270).

Almost surely, 2^21111424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21111424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22472640).

21111424 is an abundant number, since it is smaller than the sum of its proper divisors (23833856).

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

21111424 is a wasteful number, since it uses less digits than its factorization.

21111424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209 (or 197 counting only the distinct ones).

The product of its digits is 64, while the sum is 16.

The square root of 21111424 is about 4594.7169662559. The cubic root of 21111424 is about 276.3795101266.

Adding to 21111424 its reverse (42411112), we get a palindrome (63522536).

The spelling of 21111424 in words is "twenty-one million, one hundred eleven thousand, four hundred twenty-four".