21533212 has 6 divisors (see below), whose sum is σ = 37683128. Its totient is φ = 10766604.

The previous prime is 21533207. The next prime is 21533219. The reversal of 21533212 is 21233512.

It is a self number, because there is not a number n which added to its sum of digits gives 21533212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2691648 + ... + 2691655.

Almost surely, 2^21533212 is an apocalyptic number.

It is an amenable number.

21533212 is a deficient number, since it is larger than the sum of its proper divisors (16149916).

21533212 is a wasteful number, since it uses less digits than its factorization.

21533212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5383307 (or 5383305 counting only the distinct ones).

The product of its digits is 360, while the sum is 19.

The square root of 21533212 is about 4640.3892078144. The cubic root of 21533212 is about 278.2079943705.

Adding to 21533212 its reverse (21233512), we get a palindrome (42766724).

The spelling of 21533212 in words is "twenty-one million, five hundred thirty-three thousand, two hundred twelve".