21975609 has 8 divisors (see below), whose sum is σ = 30843040. Its totient is φ = 13879296.

The previous prime is 21975601. The next prime is 21975637. The reversal of 21975609 is 90657912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21975609 - 2³ = 21975601 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21975601) 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 7 ways as a sum of consecutive naturals, for example, 192712 + ... + 192825.

It is an arithmetic number, because the mean of its divisors is an integer number (3855380).

Almost surely, 2^21975609 is an apocalyptic number.

It is an amenable number.

21975609 is a deficient number, since it is larger than the sum of its proper divisors (8867431).

21975609 is a wasteful number, since it uses less digits than its factorization.

21975609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385559.

The product of its (nonzero) digits is 34020, while the sum is 39.

The square root of 21975609 is about 4687.8149494194. The cubic root of 21975609 is about 280.1003424378.

The spelling of 21975609 in words is "twenty-one million, nine hundred seventy-five thousand, six hundred nine".