21321445 has 4 divisors (see below), whose sum is σ = 25585740. Its totient is φ = 17057152.

The previous prime is 21321431. The next prime is 21321449. The reversal of 21321445 is 54412312.

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 16990884 + 4330561 = 4122^2 + 2081^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21321445 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321449) 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 in 3 ways as a sum of consecutive naturals, for example, 2132140 + ... + 2132149.

It is an arithmetic number, because the mean of its divisors is an integer number (6396435).

Almost surely, 2^21321445 is an apocalyptic number.

It is an amenable number.

21321445 is a deficient number, since it is larger than the sum of its proper divisors (4264295).

21321445 is an equidigital number, since it uses as much as digits as its factorization.

21321445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4264294.

The product of its digits is 960, while the sum is 22.

The square root of 21321445 is about 4617.5150243394. The cubic root of 21321445 is about 277.2929819803.

Adding to 21321445 its reverse (54412312), we get a palindrome (75733757).

The spelling of 21321445 in words is "twenty-one million, three hundred twenty-one thousand, four hundred forty-five".