21045361 has 4 divisors (see below), whose sum is σ = 21534832. Its totient is φ = 20555892.

The previous prime is 21045319. The next prime is 21045377. The reversal of 21045361 is 16354012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21045361 - 2¹¹ = 21043313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21045301) 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, 244671 + ... + 244756.

It is an arithmetic number, because the mean of its divisors is an integer number (5383708).

Almost surely, 2^21045361 is an apocalyptic number.

It is an amenable number.

21045361 is a deficient number, since it is larger than the sum of its proper divisors (489471).

21045361 is an equidigital number, since it uses as much as digits as its factorization.

21045361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 489470.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21045361 is about 4587.5223160220. The cubic root of 21045361 is about 276.0909217005.

Adding to 21045361 its reverse (16354012), we get a palindrome (37399373).

The spelling of 21045361 in words is "twenty-one million, forty-five thousand, three hundred sixty-one".