21108439 has 8 divisors (see below), whose sum is σ = 23112720. Its totient is φ = 19118400.

The previous prime is 21108431. The next prime is 21108497. The reversal of 21108439 is 93480112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21108439 - 2³ = 21108431 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 324 + ... + 6505.

It is an arithmetic number, because the mean of its divisors is an integer number (2889090).

Almost surely, 2^21108439 is an apocalyptic number.

21108439 is a deficient number, since it is larger than the sum of its proper divisors (2004281).

21108439 is a wasteful number, since it uses less digits than its factorization.

21108439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7121.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21108439 is about 4594.3921251891. The cubic root of 21108439 is about 276.3664835030.

The spelling of 21108439 in words is "twenty-one million, one hundred eight thousand, four hundred thirty-nine".