21512212 has 24 divisors (see below), whose sum is σ = 38790752. Its totient is φ = 10432800.

The previous prime is 21512147. The next prime is 21512213. The reversal of 21512212 is 21221512.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21512213) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30787 + ... + 31477.

Almost surely, 2^21512212 is an apocalyptic number.

It is an amenable number.

21512212 is a deficient number, since it is larger than the sum of its proper divisors (17278540).

21512212 is a wasteful number, since it uses less digits than its factorization.

21512212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 919 (or 917 counting only the distinct ones).

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

The square root of 21512212 is about 4638.1259146341. The cubic root of 21512212 is about 278.1175253136.

Adding to 21512212 its reverse (21221512), we get a palindrome (42733724).

The spelling of 21512212 in words is "twenty-one million, five hundred twelve thousand, two hundred twelve".