21636833 has 2 divisors, whose sum is σ = 21636834. Its totient is φ = 21636832.

The previous prime is 21636829. The next prime is 21636847. The reversal of 21636833 is 33863612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17405584 + 4231249 = 4172^2 + 2057^2 .

It is a cyclic number.

It is not a de Polignac number, because 21636833 - 2² = 21636829 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21636833.

It is not a weakly prime, because it can be changed into another prime (21636803) 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 as a sum of consecutive naturals, namely, 10818416 + 10818417.

It is an arithmetic number, because the mean of its divisors is an integer number (10818417).

Almost surely, 2^21636833 is an apocalyptic number.

It is an amenable number.

21636833 is a deficient number, since it is larger than the sum of its proper divisors (1).

21636833 is an equidigital number, since it uses as much as digits as its factorization.

21636833 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 32.

The square root of 21636833 is about 4651.5409274777. The cubic root of 21636833 is about 278.6535397908.

The spelling of 21636833 in words is "twenty-one million, six hundred thirty-six thousand, eight hundred thirty-three".