21828637 has 4 divisors (see below), whose sum is σ = 21841020. Its totient is φ = 21816256.

The previous prime is 21828623. The next prime is 21828659. The reversal of 21828637 is 73682812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3944196 + 17884441 = 1986^2 + 4229^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21828637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21828596 and 21828605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21828617) by changing a digit.

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, 2998 + ... + 7255.

It is an arithmetic number, because the mean of its divisors is an integer number (5460255).

Almost surely, 2^21828637 is an apocalyptic number.

It is an amenable number.

21828637 is a deficient number, since it is larger than the sum of its proper divisors (12383).

21828637 is a wasteful number, since it uses less digits than its factorization.

21828637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12382.

The product of its digits is 32256, while the sum is 37.

The square root of 21828637 is about 4672.1126912779. The cubic root of 21828637 is about 279.4745118596.

The spelling of 21828637 in words is "twenty-one million, eight hundred twenty-eight thousand, six hundred thirty-seven".