21120812 has 12 divisors (see below), whose sum is σ = 37513560. Its totient is φ = 10402656.

The previous prime is 21120811. The next prime is 21120829. The reversal of 21120812 is 21802112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21120811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39137 + ... + 39672.

It is an arithmetic number, because the mean of its divisors is an integer number (3126130).

Almost surely, 2^21120812 is an apocalyptic number.

It is an amenable number.

21120812 is a deficient number, since it is larger than the sum of its proper divisors (16392748).

21120812 is a wasteful number, since it uses less digits than its factorization.

21120812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78880 (or 78878 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 21120812 is about 4595.7384607917. The cubic root of 21120812 is about 276.4204716195.

Adding to 21120812 its reverse (21802112), we get a palindrome (42922924).

The spelling of 21120812 in words is "twenty-one million, one hundred twenty thousand, eight hundred twelve".