21504401553 has 16 divisors (see below), whose sum is σ = 29162518400. Its totient is φ = 14091598080.

The previous prime is 21504401551. The next prime is 21504401557. The reversal of 21504401553 is 35510440512.

It is not a de Polignac number, because 21504401553 - 2¹ = 21504401551 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21504401553.

It is not an unprimeable number, because it can be changed into a prime (21504401551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 233028 + ... + 311946.

It is an arithmetic number, because the mean of its divisors is an integer number (1822657400).

Almost surely, 2^21504401553 is an apocalyptic number.

It is an amenable number.

21504401553 is a deficient number, since it is larger than the sum of its proper divisors (7658116847).

21504401553 is a wasteful number, since it uses less digits than its factorization.

21504401553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80472.

The product of its (nonzero) digits is 12000, while the sum is 30.

The spelling of 21504401553 in words is "twenty-one billion, five hundred four million, four hundred one thousand, five hundred fifty-three".