21245415 has 16 divisors (see below), whose sum is σ = 34050048. Its totient is φ = 11311776.

The previous prime is 21245407. The next prime is 21245417. The reversal of 21245415 is 51454212.

It is not a de Polignac number, because 21245415 - 2³ = 21245407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15654 + ... + 16956.

It is an arithmetic number, because the mean of its divisors is an integer number (2128128).

Almost surely, 2^21245415 is an apocalyptic number.

21245415 is a deficient number, since it is larger than the sum of its proper divisors (12804633).

21245415 is a wasteful number, since it uses less digits than its factorization.

21245415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2398.

The product of its digits is 1600, while the sum is 24.

The square root of 21245415 is about 4609.2748887433. The cubic root of 21245415 is about 276.9629903592.

Adding to 21245415 its reverse (51454212), we get a palindrome (72699627).

The spelling of 21245415 in words is "twenty-one million, two hundred forty-five thousand, four hundred fifteen".