21171039 has 4 divisors (see below), whose sum is σ = 28228056. Its totient is φ = 14114024.

The previous prime is 21171037. The next prime is 21171043. The reversal of 21171039 is 93017112.

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

It is a cyclic number.

It is not a de Polignac number, because 21171039 - 2¹ = 21171037 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171037) 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, 3528504 + ... + 3528509.

It is an arithmetic number, because the mean of its divisors is an integer number (7057014).

Almost surely, 2^21171039 is an apocalyptic number.

21171039 is a deficient number, since it is larger than the sum of its proper divisors (7057017).

21171039 is an equidigital number, since it uses as much as digits as its factorization.

21171039 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7057016.

The product of its (nonzero) digits is 378, while the sum is 24.

The square root of 21171039 is about 4601.1997348518. The cubic root of 21171039 is about 276.6394149058.

It can be divided in two parts, 2117103 and 9, that added together give a palindrome (2117112).

The spelling of 21171039 in words is "twenty-one million, one hundred seventy-one thousand, thirty-nine".