21165241 has 2 divisors, whose sum is σ = 21165242. Its totient is φ = 21165240.

The previous prime is 21165229. The next prime is 21165251. The reversal of 21165241 is 14256112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21123216 + 42025 = 4596^2 + 205^2 .

It is a cyclic number.

It is not a de Polignac number, because 21165241 - 2¹³ = 21157049 is a prime.

It is not a weakly prime, because it can be changed into another prime (21165251) 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 as a sum of consecutive naturals, namely, 10582620 + 10582621.

It is an arithmetic number, because the mean of its divisors is an integer number (10582621).

Almost surely, 2^21165241 is an apocalyptic number.

It is an amenable number.

21165241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165241 is an equidigital number, since it uses as much as digits as its factorization.

21165241 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 480, while the sum is 22.

The square root of 21165241 is about 4600.5696386426. The cubic root of 21165241 is about 276.6141586777.

The spelling of 21165241 in words is "twenty-one million, one hundred sixty-five thousand, two hundred forty-one".