21250224 has 30 divisors (see below), whose sum is σ = 59471516. Its totient is φ = 7083360.

The previous prime is 21250217. The next prime is 21250253. The reversal of 21250224 is 42205212.

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 = 21250197 and 21250206.

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 5 ways as a sum of consecutive naturals, for example, 73642 + ... + 73929.

Almost surely, 2^21250224 is an apocalyptic number.

21250224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21250224 is an abundant number, since it is smaller than the sum of its proper divisors (38221292).

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

21250224 is a wasteful number, since it uses less digits than its factorization.

21250224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147585 (or 147576 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21250224 is about 4609.7965247937. The cubic root of 21250224 is about 276.9838860762.

Adding to 21250224 its reverse (42205212), we get a palindrome (63455436).

The spelling of 21250224 in words is "twenty-one million, two hundred fifty thousand, two hundred twenty-four".