21224215 has 8 divisors (see below), whose sum is σ = 25494480. Its totient is φ = 16962432.

The previous prime is 21224207. The next prime is 21224249. The reversal of 21224215 is 51242212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21224215 - 2³ = 21224207 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21224192 and 21224201.

It is a congruent number.

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, 6831 + ... + 9439.

It is an arithmetic number, because the mean of its divisors is an integer number (3186810).

Almost surely, 2^21224215 is an apocalyptic number.

21224215 is a deficient number, since it is larger than the sum of its proper divisors (4270265).

21224215 is a wasteful number, since it uses less digits than its factorization.

21224215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4241.

The product of its digits is 320, while the sum is 19.

The square root of 21224215 is about 4606.9746037937. The cubic root of 21224215 is about 276.8708360520.

Adding to 21224215 its reverse (51242212), we get a palindrome (72466427).

The spelling of 21224215 in words is "twenty-one million, two hundred twenty-four thousand, two hundred fifteen".