21210241 has 4 divisors (see below), whose sum is σ = 22841812. Its totient is φ = 19578672.

The previous prime is 21210227. The next prime is 21210269. The reversal of 21210241 is 14201212.

It is a happy number.

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 4161600 + 17048641 = 2040^2 + 4129^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210241 - 2¹⁵ = 21177473 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 1631557 = 21210241 / (2 + 1 + 2 + 1 + 0 + 2 + 4 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21210221) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 815766 + ... + 815791.

It is an arithmetic number, because the mean of its divisors is an integer number (5710453).

Almost surely, 2^21210241 is an apocalyptic number.

It is an amenable number.

21210241 is a deficient number, since it is larger than the sum of its proper divisors (1631571).

21210241 is a wasteful number, since it uses less digits than its factorization.

21210241 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1631570.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21210241 is about 4605.4577405509. The cubic root of 21210241 is about 276.8100588928.

Adding to 21210241 its reverse (14201212), we get a palindrome (35411453).

The spelling of 21210241 in words is "twenty-one million, two hundred ten thousand, two hundred forty-one".