21126573 has 12 divisors (see below), whose sum is σ = 32863740. Its totient is φ = 13000896.

The previous prime is 21126569. The next prime is 21126583. The reversal of 21126573 is 37562112.

It is a happy number.

21126573 is a `hidden beast` number, since 2 + 1 + 1 + 2 + 657 + 3 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 9715689 + 11410884 = 3117^2 + 3378^2 .

It is not a de Polignac number, because 21126573 - 2² = 21126569 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21126533) 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, 90168 + ... + 90401.

It is an arithmetic number, because the mean of its divisors is an integer number (2738645).

Almost surely, 2^21126573 is an apocalyptic number.

It is an amenable number.

21126573 is a deficient number, since it is larger than the sum of its proper divisors (11737167).

21126573 is a wasteful number, since it uses less digits than its factorization.

21126573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180588 (or 180585 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21126573 is about 4596.3651943683. The cubic root of 21126573 is about 276.4456018650.

Adding to 21126573 its reverse (37562112), we get a palindrome (58688685).

The spelling of 21126573 in words is "twenty-one million, one hundred twenty-six thousand, five hundred seventy-three".