21244215 has 16 divisors (see below), whose sum is σ = 34090848. Its totient is φ = 11296896.

The previous prime is 21244213. The next prime is 21244217. The reversal of 21244215 is 51244212.

It is an interprime number because it is at equal distance from previous prime (21244213) and next prime (21244217).

It is not a de Polignac number, because 21244215 - 2¹ = 21244213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21244191 and 21244200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21244213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3697 + ... + 7493.

It is an arithmetic number, because the mean of its divisors is an integer number (2130678).

Almost surely, 2^21244215 is an apocalyptic number.

21244215 is a deficient number, since it is larger than the sum of its proper divisors (12846633).

21244215 is a wasteful number, since it uses less digits than its factorization.

21244215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4178.

The product of its digits is 640, while the sum is 21.

The square root of 21244215 is about 4609.1447145864. The cubic root of 21244215 is about 276.9577757149.

Adding to 21244215 its reverse (51244212), we get a palindrome (72488427).

The spelling of 21244215 in words is "twenty-one million, two hundred forty-four thousand, two hundred fifteen".