21165105 has 32 divisors (see below), whose sum is σ = 36691200. Its totient is φ = 10356480.

The previous prime is 21165097. The next prime is 21165121. The reversal of 21165105 is 50156112.

It is not a de Polignac number, because 21165105 - 2³ = 21165097 is a prime.

It is a super-2 number, since 2×21165105² = 895923339322050, which contains 22 as substring.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 60471 + ... + 60819.

It is an arithmetic number, because the mean of its divisors is an integer number (1146600).

Almost surely, 2^21165105 is an apocalyptic number.

It is an amenable number.

21165105 is a deficient number, since it is larger than the sum of its proper divisors (15526095).

21165105 is a wasteful number, since it uses less digits than its factorization.

21165105 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681.

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 21165105 is about 4600.5548578405. The cubic root of 21165105 is about 276.6135662030.

The spelling of 21165105 in words is "twenty-one million, one hundred sixty-five thousand, one hundred five".