21240543 has 4 divisors (see below), whose sum is σ = 28320728. Its totient is φ = 14160360.

The previous prime is 21240539. The next prime is 21240547. The reversal of 21240543 is 34504212.

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

It is an interprime number because it is at equal distance from previous prime (21240539) and next prime (21240547).

It is not a de Polignac number, because 21240543 - 2² = 21240539 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21240547) 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, 3540088 + ... + 3540093.

It is an arithmetic number, because the mean of its divisors is an integer number (7080182).

Almost surely, 2^21240543 is an apocalyptic number.

21240543 is a deficient number, since it is larger than the sum of its proper divisors (7080185).

21240543 is an equidigital number, since it uses as much as digits as its factorization.

21240543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7080184.

The product of its (nonzero) digits is 960, while the sum is 21.

The square root of 21240543 is about 4608.7463588269. The cubic root of 21240543 is about 276.9418176835.

Adding to 21240543 its reverse (34504212), we get a palindrome (55744755).

It can be divided in two parts, 212 and 40543, that added together give a triangular number (40755 = T₂₈₅).

The spelling of 21240543 in words is "twenty-one million, two hundred forty thousand, five hundred forty-three".