21115173 has 32 divisors (see below), whose sum is σ = 31850496. Its totient is φ = 12370688.

The previous prime is 21115141. The next prime is 21115189. The reversal of 21115173 is 37151112.

It is a happy number.

It is not a de Polignac number, because 21115173 - 2⁵ = 21115141 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115373) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 54940 + ... + 55322.

It is an arithmetic number, because the mean of its divisors is an integer number (995328).

Almost surely, 2^21115173 is an apocalyptic number.

21115173 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21115173 is a deficient number, since it is larger than the sum of its proper divisors (10735323).

21115173 is a wasteful number, since it uses less digits than its factorization.

21115173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473.

The product of its digits is 210, while the sum is 21.

The square root of 21115173 is about 4595.1249166916. The cubic root of 21115173 is about 276.3958691282.

Adding to 21115173 its reverse (37151112), we get a palindrome (58266285).

The spelling of 21115173 in words is "twenty-one million, one hundred fifteen thousand, one hundred seventy-three".