21302243 has 4 divisors (see below), whose sum is σ = 21797688. Its totient is φ = 20806800.

The previous prime is 21302227. The next prime is 21302251. The reversal of 21302243 is 34220312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21302243 - 2⁴ = 21302227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21302273) 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, 247658 + ... + 247743.

It is an arithmetic number, because the mean of its divisors is an integer number (5449422).

Almost surely, 2^21302243 is an apocalyptic number.

21302243 is a deficient number, since it is larger than the sum of its proper divisors (495445).

21302243 is an equidigital number, since it uses as much as digits as its factorization.

21302243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495444.

The product of its (nonzero) digits is 288, while the sum is 17.

The square root of 21302243 is about 4615.4352990807. The cubic root of 21302243 is about 277.2097140300.

Adding to 21302243 its reverse (34220312), we get a palindrome (55522555).

The spelling of 21302243 in words is "twenty-one million, three hundred two thousand, two hundred forty-three".