21828537 has 12 divisors (see below), whose sum is σ = 31577364. Its totient is φ = 14530560.

The previous prime is 21828529. The next prime is 21828551. The reversal of 21828537 is 73582812.

It can be written as a sum of positive squares in 2 ways, for example, as 12702096 + 9126441 = 3564^2 + 3021^2 .

It is not a de Polignac number, because 21828537 - 2³ = 21828529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21828517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6553 + ... + 9305.

It is an arithmetic number, because the mean of its divisors is an integer number (2631447).

Almost surely, 2^21828537 is an apocalyptic number.

It is an amenable number.

21828537 is a deficient number, since it is larger than the sum of its proper divisors (9748827).

21828537 is a wasteful number, since it uses less digits than its factorization.

21828537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3640 (or 3637 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 21828537 is about 4672.1019894690. The cubic root of 21828537 is about 279.4740850885.

The spelling of 21828537 in words is "twenty-one million, eight hundred twenty-eight thousand, five hundred thirty-seven".