21103173 has 60 divisors (see below), whose sum is σ = 39588780. Its totient is φ = 11104128.

The previous prime is 21103139. The next prime is 21103177. The reversal of 21103173 is 37130112.

It can be written as a sum of positive squares in 2 ways, for example, as 11573604 + 9529569 = 3402^2 + 3087^2 .

It is not a de Polignac number, because 21103173 - 2⁶ = 21103109 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21103177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 51393 + ... + 51801.

It is an arithmetic number, because the mean of its divisors is an integer number (659813).

Almost surely, 2^21103173 is an apocalyptic number.

It is an amenable number.

21103173 is a deficient number, since it is larger than the sum of its proper divisors (18485607).

21103173 is a wasteful number, since it uses less digits than its factorization.

21103173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448 (or 432 counting only the distinct ones).

The product of its (nonzero) digits is 126, while the sum is 18.

The square root of 21103173 is about 4593.8189994818. The cubic root of 21103173 is about 276.3434995368.

Adding to 21103173 its reverse (37130112), we get a palindrome (58233285).

The spelling of 21103173 in words is "twenty-one million, one hundred three thousand, one hundred seventy-three".