21072241 has 4 divisors (see below), whose sum is σ = 21798900. Its totient is φ = 20345584.

The previous prime is 21072239. The next prime is 21072251. The reversal of 21072241 is 14227012.

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 5271616 + 15800625 = 2296^2 + 3975^2 .

It is a cyclic number.

It is not a de Polignac number, because 21072241 - 2¹ = 21072239 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21072211) 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, 363286 + ... + 363343.

It is an arithmetic number, because the mean of its divisors is an integer number (5449725).

Almost surely, 2^21072241 is an apocalyptic number.

It is an amenable number.

21072241 is a deficient number, since it is larger than the sum of its proper divisors (726659).

21072241 is an equidigital number, since it uses as much as digits as its factorization.

21072241 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 726658.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 21072241 is about 4590.4510671610. The cubic root of 21072241 is about 276.2084165823.

Adding to 21072241 its reverse (14227012), we get a palindrome (35299253).

The spelling of 21072241 in words is "twenty-one million, seventy-two thousand, two hundred forty-one".