21125812 has 12 divisors (see below), whose sum is σ = 37067940. Its totient is φ = 10534976.

The previous prime is 21125803. The next prime is 21125843. The reversal of 21125812 is 21852112.

It can be written as a sum of positive squares in 2 ways, for example, as 13868176 + 7257636 = 3724^2 + 2694^2 .

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, 5233 + ... + 8344.

It is an arithmetic number, because the mean of its divisors is an integer number (3088995).

Almost surely, 2^21125812 is an apocalyptic number.

It is an amenable number.

21125812 is a deficient number, since it is larger than the sum of its proper divisors (15942128).

21125812 is a wasteful number, since it uses less digits than its factorization.

21125812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13970 (or 13968 counting only the distinct ones).

The product of its digits is 320, while the sum is 22.

The square root of 21125812 is about 4596.2824108186. The cubic root of 21125812 is about 276.4422825440.

Adding to 21125812 its reverse (21852112), we get a palindrome (42977924).

The spelling of 21125812 in words is "twenty-one million, one hundred twenty-five thousand, eight hundred twelve".