21193243 has 4 divisors (see below), whose sum is σ = 21876928. Its totient is φ = 20509560.

The previous prime is 21193231. The next prime is 21193247. The reversal of 21193243 is 34239112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21193243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21193247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 341796 + ... + 341857.

It is an arithmetic number, because the mean of its divisors is an integer number (5469232).

Almost surely, 2^21193243 is an apocalyptic number.

21193243 is a deficient number, since it is larger than the sum of its proper divisors (683685).

21193243 is an equidigital number, since it uses as much as digits as its factorization.

21193243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 683684.

The product of its digits is 1296, while the sum is 25.

The square root of 21193243 is about 4603.6119515007. The cubic root of 21193243 is about 276.7360934458.

The spelling of 21193243 in words is "twenty-one million, one hundred ninety-three thousand, two hundred forty-three".