21754243 has 4 divisors (see below), whose sum is σ = 24862000. Its totient is φ = 18646488.

The previous prime is 21754207. The next prime is 21754283. The reversal of 21754243 is 34245712.

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

It is not a de Polignac number, because 21754243 - 2⁹ = 21753731 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21754283) 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, 1553868 + ... + 1553881.

It is an arithmetic number, because the mean of its divisors is an integer number (6215500).

Almost surely, 2^21754243 is an apocalyptic number.

21754243 is a deficient number, since it is larger than the sum of its proper divisors (3107757).

21754243 is an equidigital number, since it uses as much as digits as its factorization.

21754243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3107756.

The product of its digits is 6720, while the sum is 28.

The square root of 21754243 is about 4664.1444017097. The cubic root of 21754243 is about 279.1566588922.

Adding to 21754243 its reverse (34245712), we get a palindrome (55999955).

The spelling of 21754243 in words is "twenty-one million, seven hundred fifty-four thousand, two hundred forty-three".