21228824 has 16 divisors (see below), whose sum is σ = 40880400. Its totient is φ = 10327392.

The previous prime is 21228811. The next prime is 21228829. The reversal of 21228824 is 42882212.

It is a super-4 number, since 4×21228824⁴ (a number of 30 digits) contains 4444 as substring.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228829) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35564 + ... + 36155.

It is an arithmetic number, because the mean of its divisors is an integer number (2555025).

Almost surely, 2^21228824 is an apocalyptic number.

It is an amenable number.

21228824 is a deficient number, since it is larger than the sum of its proper divisors (19651576).

21228824 is a wasteful number, since it uses less digits than its factorization.

21228824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71762 (or 71758 counting only the distinct ones).

The product of its digits is 4096, while the sum is 29.

The square root of 21228824 is about 4607.4747964585. The cubic root of 21228824 is about 276.8908761387.

The spelling of 21228824 in words is "twenty-one million, two hundred twenty-eight thousand, eight hundred twenty-four".