21105542553 has 16 divisors (see below), whose sum is σ = 29573413056. Its totient is φ = 13371704640.

The previous prime is 21105542477. The next prime is 21105542567. The reversal of 21105542553 is 35524550112.

It is not a de Polignac number, because 21105542553 - 2¹⁰ = 21105541529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21105542053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2206158 + ... + 2215703.

It is an arithmetic number, because the mean of its divisors is an integer number (1848338316).

Almost surely, 2^21105542553 is an apocalyptic number.

It is an amenable number.

21105542553 is a deficient number, since it is larger than the sum of its proper divisors (8467870503).

21105542553 is a wasteful number, since it uses less digits than its factorization.

21105542553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4421944.

The product of its (nonzero) digits is 30000, while the sum is 33.

The spelling of 21105542553 in words is "twenty-one billion, one hundred five million, five hundred forty-two thousand, five hundred fifty-three".