21215212 has 12 divisors (see below), whose sum is σ = 37182040. Its totient is φ = 10591776.

The previous prime is 21215203. The next prime is 21215221. The reversal of 21215212 is 21251212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21215203) and next prime (21215221).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 633 + ... + 6544.

Almost surely, 2^21215212 is an apocalyptic number.

It is an amenable number.

21215212 is a deficient number, since it is larger than the sum of its proper divisors (15966828).

21215212 is a wasteful number, since it uses less digits than its factorization.

21215212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7920 (or 7918 counting only the distinct ones).

The product of its digits is 80, while the sum is 16.

The square root of 21215212 is about 4605.9973947018. The cubic root of 21215212 is about 276.8316823359.

Adding to 21215212 its reverse (21251212), we get a palindrome (42466424).

The spelling of 21215212 in words is "twenty-one million, two hundred fifteen thousand, two hundred twelve".