21215230 has 16 divisors (see below), whose sum is σ = 38350224. Its totient is φ = 8449920.

The previous prime is 21215221. The next prime is 21215231. The reversal of 21215230 is 3251212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21215231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1992 + ... + 6811.

It is an arithmetic number, because the mean of its divisors is an integer number (2396889).

Almost surely, 2^21215230 is an apocalyptic number.

21215230 is a deficient number, since it is larger than the sum of its proper divisors (17134994).

21215230 is a wasteful number, since it uses less digits than its factorization.

21215230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9051.

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

The square root of 21215230 is about 4605.9993486756. Note that the first 3 decimals coincide. The cubic root of 21215230 is about 276.8317606282.

Adding to 21215230 its reverse (3251212), we get a palindrome (24466442).

The spelling of 21215230 in words is "twenty-one million, two hundred fifteen thousand, two hundred thirty".