21109989 has 8 divisors (see below), whose sum is σ = 28206400. Its totient is φ = 14043456.

The previous prime is 21109987. The next prime is 21110027. The reversal of 21109989 is 98990112.

It is a happy number.

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

It is not a de Polignac number, because 21109989 - 2¹ = 21109987 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21109987) 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 in 7 ways as a sum of consecutive naturals, for example, 5764 + ... + 8685.

It is an arithmetic number, because the mean of its divisors is an integer number (3525800).

Almost surely, 2^21109989 is an apocalyptic number.

It is an amenable number.

21109989 is a deficient number, since it is larger than the sum of its proper divisors (7096411).

21109989 is a wasteful number, since it uses less digits than its factorization.

21109989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14939.

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 21109989 is about 4594.5608059966. The cubic root of 21109989 is about 276.3732478997.

The spelling of 21109989 in words is "twenty-one million, one hundred nine thousand, nine hundred eighty-nine".