21103165 has 16 divisors (see below), whose sum is σ = 25857216. Its totient is φ = 16531200.

The previous prime is 21103139. The next prime is 21103177. The reversal of 21103165 is 56130112.

It is a de Polignac number, because none of the positive numbers 2^k-21103165 is a prime.

It is a Duffinian number.

21103165 is a modest number, since divided by 3165 gives 2110 as remainder.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 87445 + ... + 87685.

It is an arithmetic number, because the mean of its divisors is an integer number (1616076).

Almost surely, 2^21103165 is an apocalyptic number.

It is an amenable number.

21103165 is a deficient number, since it is larger than the sum of its proper divisors (4754051).

21103165 is a wasteful number, since it uses less digits than its factorization.

21103165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540.

The product of its (nonzero) digits is 180, while the sum is 19.

The square root of 21103165 is about 4593.8181287465. The cubic root of 21103165 is about 276.3434646171.

Adding to 21103165 its reverse (56130112), we get a palindrome (77233277).

The spelling of 21103165 in words is "twenty-one million, one hundred three thousand, one hundred sixty-five".