21201165 has 12 divisors (see below), whose sum is σ = 36748764. Its totient is φ = 11307264.

The previous prime is 21201157. The next prime is 21201197. The reversal of 21201165 is 56110212.

It can be written as a sum of positive squares in 2 ways, for example, as 13682601 + 7518564 = 3699^2 + 2742^2 .

It is not a de Polignac number, because 21201165 - 2³ = 21201157 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 235524 + ... + 235613.

It is an arithmetic number, because the mean of its divisors is an integer number (3062397).

Almost surely, 2^21201165 is an apocalyptic number.

It is an amenable number.

21201165 is a deficient number, since it is larger than the sum of its proper divisors (15547599).

21201165 is a wasteful number, since it uses less digits than its factorization.

21201165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 471148 (or 471145 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21201165 is about 4604.4722824663. The cubic root of 21201165 is about 276.7705703186.

Adding to 21201165 its reverse (56110212), we get a palindrome (77311377).

The spelling of 21201165 in words is "twenty-one million, two hundred one thousand, one hundred sixty-five".