21304215 has 40 divisors (see below), whose sum is σ = 39151728. Its totient is φ = 11076480.

The previous prime is 21304147. The next prime is 21304219. The reversal of 21304215 is 51240312.

It is not a de Polignac number, because 21304215 - 2¹² = 21300119 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21304219) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 15964 + ... + 17246.

Almost surely, 2^21304215 is an apocalyptic number.

21304215 is a deficient number, since it is larger than the sum of its proper divisors (17847513).

21304215 is a wasteful number, since it uses less digits than its factorization.

21304215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21304215 is about 4615.6489251242. The cubic root of 21304215 is about 277.2182677566.

Adding to 21304215 its reverse (51240312), we get a palindrome (72544527).

The spelling of 21304215 in words is "twenty-one million, three hundred four thousand, two hundred fifteen".