21975849 has 48 divisors (see below), whose sum is σ = 39087360. Its totient is φ = 11652480.

The previous prime is 21975841. The next prime is 21975851. The reversal of 21975849 is 94857912.

It is not a de Polignac number, because 21975849 - 2³ = 21975841 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

Its product of digits (181440) is a multiple of the sum of its prime factors (135).

It is not an unprimeable number, because it can be changed into a prime (21975841) 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 47 ways as a sum of consecutive naturals, for example, 309484 + ... + 309554.

It is an arithmetic number, because the mean of its divisors is an integer number (814320).

Almost surely, 2^21975849 is an apocalyptic number.

It is an amenable number.

21975849 is a deficient number, since it is larger than the sum of its proper divisors (17111511).

21975849 is an equidigital number, since it uses as much as digits as its factorization.

21975849 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135 (or 98 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 21975849 is about 4687.8405476296. The cubic root of 21975849 is about 280.1013621112.

The spelling of 21975849 in words is "twenty-one million, nine hundred seventy-five thousand, eight hundred forty-nine".