21303445 has 4 divisors (see below), whose sum is σ = 25564140. Its totient is φ = 17042752.

The previous prime is 21303421. The next prime is 21303467. The reversal of 21303445 is 54430312.

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 6380676 + 14922769 = 2526^2 + 3863^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21303445 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2130340 + ... + 2130349.

It is an arithmetic number, because the mean of its divisors is an integer number (6391035).

Almost surely, 2^21303445 is an apocalyptic number.

It is an amenable number.

21303445 is a deficient number, since it is larger than the sum of its proper divisors (4260695).

21303445 is an equidigital number, since it uses as much as digits as its factorization.

21303445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4260694.

The product of its (nonzero) digits is 1440, while the sum is 22.

The square root of 21303445 is about 4615.5655124806. The cubic root of 21303445 is about 277.2149278754.

Adding to 21303445 its reverse (54430312), we get a palindrome (75733757).

The spelling of 21303445 in words is "twenty-one million, three hundred three thousand, four hundred forty-five".