21166568 has 16 divisors (see below), whose sum is σ = 39790500. Its totient is φ = 10555776.

The previous prime is 21166567. The next prime is 21166597. The reversal of 21166568 is 86566112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21141604 + 24964 = 4598^2 + 158^2 .

It is not an unprimeable number, because it can be changed into a prime (21166567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38 + ... + 6506.

Almost surely, 2^21166568 is an apocalyptic number.

It is an amenable number.

21166568 is a deficient number, since it is larger than the sum of its proper divisors (18623932).

21166568 is a wasteful number, since it uses less digits than its factorization.

21166568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6884 (or 6880 counting only the distinct ones).

The product of its digits is 17280, while the sum is 35.

The square root of 21166568 is about 4600.7138576530. The cubic root of 21166568 is about 276.6199395287.

The spelling of 21166568 in words is "twenty-one million, one hundred sixty-six thousand, five hundred sixty-eight".