21636573 has 32 divisors (see below), whose sum is σ = 35005440. Its totient is φ = 11612160.

The previous prime is 21636557. The next prime is 21636617. The reversal of 21636573 is 37563612.

It is not a de Polignac number, because 21636573 - 2⁴ = 21636557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636533) 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 31 ways as a sum of consecutive naturals, for example, 84061 + ... + 84317.

It is an arithmetic number, because the mean of its divisors is an integer number (1093920).

Almost surely, 2^21636573 is an apocalyptic number.

It is an amenable number.

21636573 is a deficient number, since it is larger than the sum of its proper divisors (13368867).

21636573 is a wasteful number, since it uses less digits than its factorization.

21636573 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 497.

The product of its digits is 22680, while the sum is 33.

The square root of 21636573 is about 4651.5129796659. The cubic root of 21636573 is about 278.6524236353.

The spelling of 21636573 in words is "twenty-one million, six hundred thirty-six thousand, five hundred seventy-three".