21543412555 has 16 divisors (see below), whose sum is σ = 30564054720. Its totient is φ = 14263224192.

The previous prime is 21543412531. The next prime is 21543412573. The reversal of 21543412555 is 55521434512.

It is not a de Polignac number, because 21543412555 - 2¹⁵ = 21543379787 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10611504 + ... + 10613533.

It is an arithmetic number, because the mean of its divisors is an integer number (1910253420).

Almost surely, 2^21543412555 is an apocalyptic number.

21543412555 is a deficient number, since it is larger than the sum of its proper divisors (9020642165).

21543412555 is a wasteful number, since it uses less digits than its factorization.

21543412555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21225078.

The product of its digits is 120000, while the sum is 37.

The spelling of 21543412555 in words is "twenty-one billion, five hundred forty-three million, four hundred twelve thousand, five hundred fifty-five".