21445543 has 8 divisors (see below), whose sum is σ = 24574112. Its totient is φ = 18333216.

The previous prime is 21445537. The next prime is 21445573. The reversal of 21445543 is 34554412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21445543 - 2⁵ = 21445511 is a prime.

It is a super-2 number, since 2×21445543² = 919822629129698, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21445513) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1080 + ... + 6637.

It is an arithmetic number, because the mean of its divisors is an integer number (3071764).

Almost surely, 2^21445543 is an apocalyptic number.

21445543 is a deficient number, since it is larger than the sum of its proper divisors (3128569).

21445543 is an equidigital number, since it uses as much as digits as its factorization.

21445543 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8121.

The product of its digits is 9600, while the sum is 28.

The square root of 21445543 is about 4630.9332752697. The cubic root of 21445543 is about 277.8299211564.

Adding to 21445543 its reverse (34554412), we get a palindrome (55999955).

The spelling of 21445543 in words is "twenty-one million, four hundred forty-five thousand, five hundred forty-three".