21230215 has 4 divisors (see below), whose sum is σ = 25476264. Its totient is φ = 16984168.

The previous prime is 21230213. The next prime is 21230227. The reversal of 21230215 is 51203212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21230215 - 2¹ = 21230213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21230213) 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 3 ways as a sum of consecutive naturals, for example, 2123017 + ... + 2123026.

It is an arithmetic number, because the mean of its divisors is an integer number (6369066).

Almost surely, 2^21230215 is an apocalyptic number.

21230215 is a deficient number, since it is larger than the sum of its proper divisors (4246049).

21230215 is an equidigital number, since it uses as much as digits as its factorization.

21230215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4246048.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21230215 is about 4607.6257443503. The cubic root of 21230215 is about 276.8969236836.

Adding to 21230215 its reverse (51203212), we get a palindrome (72433427).

The spelling of 21230215 in words is "twenty-one million, two hundred thirty thousand, two hundred fifteen".