21215512 has 16 divisors (see below), whose sum is σ = 40704840. Its totient is φ = 10360896.

The previous prime is 21215503. The next prime is 21215539. The reversal of 21215512 is 21551212.

It is a self number, because there is not a number n which added to its sum of digits gives 21215512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30493 + ... + 31180.

Almost surely, 2^21215512 is an apocalyptic number.

It is an amenable number.

21215512 is a deficient number, since it is larger than the sum of its proper divisors (19489328).

21215512 is a wasteful number, since it uses less digits than its factorization.

21215512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61722 (or 61718 counting only the distinct ones).

The product of its digits is 200, while the sum is 19.

The square root of 21215512 is about 4606.0299608231. The cubic root of 21215512 is about 276.8329872032.

Adding to 21215512 its reverse (21551212), we get a palindrome (42766724).

The spelling of 21215512 in words is "twenty-one million, two hundred fifteen thousand, five hundred twelve".