21539118 has 8 divisors (see below), whose sum is σ = 43078248. Its totient is φ = 7179704.

The previous prime is 21539107. The next prime is 21539137. The reversal of 21539118 is 81193512.

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

21539118 is an admirable number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 1794921 + ... + 1794932.

It is an arithmetic number, because the mean of its divisors is an integer number (5384781).

Almost surely, 2^21539118 is an apocalyptic number.

21539118 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21539118 is a wasteful number, since it uses less digits than its factorization.

21539118 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3589858.

The product of its digits is 2160, while the sum is 30.

The square root of 21539118 is about 4641.0255332200. The cubic root of 21539118 is about 278.2334271178.

The spelling of 21539118 in words is "twenty-one million, five hundred thirty-nine thousand, one hundred eighteen".