21418543 has 4 divisors (see below), whose sum is σ = 22349808. Its totient is φ = 20487280.

The previous prime is 21418531. The next prime is 21418571. The reversal of 21418543 is 34581412.

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 21418543 - 2¹³ = 21410351 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21418513) 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, 465598 + ... + 465643.

It is an arithmetic number, because the mean of its divisors is an integer number (5587452).

Almost surely, 2^21418543 is an apocalyptic number.

21418543 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21418543 is a deficient number, since it is larger than the sum of its proper divisors (931265).

21418543 is an equidigital number, since it uses as much as digits as its factorization.

21418543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 931264.

The product of its digits is 3840, while the sum is 28.

The square root of 21418543 is about 4628.0171780148. The cubic root of 21418543 is about 277.7132759686.

Adding to 21418543 its reverse (34581412), we get a palindrome (55999955).

The spelling of 21418543 in words is "twenty-one million, four hundred eighteen thousand, five hundred forty-three".