21543023405 has 8 divisors (see below), whose sum is σ = 25880910432. Its totient is φ = 17214897168.

The previous prime is 21543023387. The next prime is 21543023413. The reversal of 21543023405 is 50432034512.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21543023405 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 2435339 + ... + 2444168.

It is an arithmetic number, because the mean of its divisors is an integer number (3235113804).

Almost surely, 2^21543023405 is an apocalyptic number.

It is an amenable number.

21543023405 is a deficient number, since it is larger than the sum of its proper divisors (4337887027).

21543023405 is an equidigital number, since it uses as much as digits as its factorization.

21543023405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4880395.

The product of its (nonzero) digits is 14400, while the sum is 29.

Adding to 21543023405 its reverse (50432034512), we get a palindrome (71975057917).

The spelling of 21543023405 in words is "twenty-one billion, five hundred forty-three million, twenty-three thousand, four hundred five".