21016224 has 36 divisors (see below), whose sum is σ = 59765706. Its totient is φ = 7005312.

The previous prime is 21016217. The next prime is 21016241. The reversal of 21016224 is 42261012.

It can be written as a sum of positive squares in only one way, i.e., 18766224 + 2250000 = 4332^2 + 1500^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21016197 and 21016206.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36199 + ... + 36774.

Almost surely, 2^21016224 is an apocalyptic number.

21016224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21016224 is an abundant number, since it is smaller than the sum of its proper divisors (38749482).

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

21016224 is a wasteful number, since it uses less digits than its factorization.

21016224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72989 (or 72978 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21016224 is about 4584.3455367151. The cubic root of 21016224 is about 275.9634482156.

Adding to 21016224 its reverse (42261012), we get a palindrome (63277236).

The spelling of 21016224 in words is "twenty-one million, sixteen thousand, two hundred twenty-four".