21039005 has 16 divisors (see below), whose sum is σ = 27600384. Its totient is φ = 15301440.

The previous prime is 21039001. The next prime is 21039079. The reversal of 21039005 is 50093012.

It is not a de Polignac number, because 21039005 - 2² = 21039001 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 (21039001) 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 15 ways as a sum of consecutive naturals, for example, 1940 + ... + 6770.

It is an arithmetic number, because the mean of its divisors is an integer number (1725024).

Almost surely, 2^21039005 is an apocalyptic number.

It is an amenable number.

21039005 is a deficient number, since it is larger than the sum of its proper divisors (6561379).

21039005 is a wasteful number, since it uses less digits than its factorization.

21039005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4916.

The product of its (nonzero) digits is 270, while the sum is 20.

The square root of 21039005 is about 4586.8295150354. The cubic root of 21039005 is about 276.0631244330.

The spelling of 21039005 in words is "twenty-one million, thirty-nine thousand, five".