21299165 has 4 divisors (see below), whose sum is σ = 25559004. Its totient is φ = 17039328.

The previous prime is 21299153. The next prime is 21299167. The reversal of 21299165 is 56199212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9174841 + 12124324 = 3029^2 + 3482^2 .

It is a cyclic number.

It is not a de Polignac number, because 21299165 - 2⁴ = 21299149 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21299167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2129912 + ... + 2129921.

It is an arithmetic number, because the mean of its divisors is an integer number (6389751).

Almost surely, 2^21299165 is an apocalyptic number.

It is an amenable number.

21299165 is a deficient number, since it is larger than the sum of its proper divisors (4259839).

21299165 is an equidigital number, since it uses as much as digits as its factorization.

21299165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4259838.

The product of its digits is 9720, while the sum is 35.

The square root of 21299165 is about 4615.1018406965. The cubic root of 21299165 is about 277.1963618742.

The spelling of 21299165 in words is "twenty-one million, two hundred ninety-nine thousand, one hundred sixty-five".