21039087 has 4 divisors (see below), whose sum is σ = 28052120. Its totient is φ = 14026056.

The previous prime is 21039079. The next prime is 21039091. The reversal of 21039087 is 78093012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21039087 - 2³ = 21039079 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 (21039097) 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 3 ways as a sum of consecutive naturals, for example, 3506512 + ... + 3506517.

It is an arithmetic number, because the mean of its divisors is an integer number (7013030).

Almost surely, 2^21039087 is an apocalyptic number.

21039087 is a deficient number, since it is larger than the sum of its proper divisors (7013033).

21039087 is an equidigital number, since it uses as much as digits as its factorization.

21039087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7013032.

The product of its (nonzero) digits is 3024, while the sum is 30.

The square root of 21039087 is about 4586.8384536628. The cubic root of 21039087 is about 276.0634830866.

The spelling of 21039087 in words is "twenty-one million, thirty-nine thousand, eighty-seven".