21808935 has 12 divisors (see below), whose sum is σ = 37802232. Its totient is φ = 11631408.

The previous prime is 21808933. The next prime is 21808939. The reversal of 21808935 is 53980812.

It is not a de Polignac number, because 21808935 - 2¹ = 21808933 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21808935.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808933) 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, 242277 + ... + 242366.

It is an arithmetic number, because the mean of its divisors is an integer number (3150186).

Almost surely, 2^21808935 is an apocalyptic number.

21808935 is a deficient number, since it is larger than the sum of its proper divisors (15993297).

21808935 is a wasteful number, since it uses less digits than its factorization.

21808935 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 484654 (or 484651 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21808935 is about 4670.0037473218. The cubic root of 21808935 is about 279.3904042375.

The spelling of 21808935 in words is "twenty-one million, eight hundred eight thousand, nine hundred thirty-five".