21636071 has 4 divisors (see below), whose sum is σ = 21663000. Its totient is φ = 21609144.

The previous prime is 21636049. The next prime is 21636073. The reversal of 21636071 is 17063612.

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

It is a cyclic number.

It is not a de Polignac number, because 21636071 - 2⁶ = 21636007 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21636071.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636073) 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 3 ways as a sum of consecutive naturals, for example, 12221 + ... + 13878.

It is an arithmetic number, because the mean of its divisors is an integer number (5415750).

Almost surely, 2^21636071 is an apocalyptic number.

21636071 is a deficient number, since it is larger than the sum of its proper divisors (26929).

21636071 is an equidigital number, since it uses as much as digits as its factorization.

21636071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26928.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21636071 is about 4651.4590184156. The cubic root of 21636071 is about 278.6502685713.

Adding to 21636071 its reverse (17063612), we get a palindrome (38699683).

The spelling of 21636071 in words is "twenty-one million, six hundred thirty-six thousand, seventy-one".