21109239 has 12 divisors (see below), whose sum is σ = 31817136. Its totient is φ = 13460832.

The previous prime is 21109229. The next prime is 21109241. The reversal of 21109239 is 93290112.

It is not a de Polignac number, because 21109239 - 2²¹ = 19012087 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21109229) 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 11 ways as a sum of consecutive naturals, for example, 50782 + ... + 51195.

It is an arithmetic number, because the mean of its divisors is an integer number (2651428).

Almost surely, 2^21109239 is an apocalyptic number.

21109239 is a deficient number, since it is larger than the sum of its proper divisors (10707897).

21109239 is a wasteful number, since it uses less digits than its factorization.

21109239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102006 (or 102003 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 21109239 is about 4594.4791870244. The cubic root of 21109239 is about 276.3699748458.

The spelling of 21109239 in words is "twenty-one million, one hundred nine thousand, two hundred thirty-nine".