21166065 has 24 divisors (see below), whose sum is σ = 37059048. Its totient is φ = 11174400.

The previous prime is 21166051. The next prime is 21166099. The reversal of 21166065 is 56066112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 3196944 + 17969121 = 1788^2 + 4239^2 .

It is not a de Polignac number, because 21166065 - 2¹⁶ = 21100529 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2217 + ... + 6873.

It is an arithmetic number, because the mean of its divisors is an integer number (1544127).

Almost surely, 2^21166065 is an apocalyptic number.

It is an amenable number.

21166065 is a deficient number, since it is larger than the sum of its proper divisors (15892983).

21166065 is a wasteful number, since it uses less digits than its factorization.

21166065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4769 (or 4766 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21166065 is about 4600.6591918985. The cubic root of 21166065 is about 276.6177483228.

The spelling of 21166065 in words is "twenty-one million, one hundred sixty-six thousand, sixty-five".