21455005105553 has 4 divisors (see below), whose sum is σ = 21806726500788. Its totient is φ = 21103283710320.

The previous prime is 21455005105507. The next prime is 21455005105579. The reversal of 21455005105553 is 35550150055412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2668051095889 + 18786954009664 = 1633417^2 + 4334392^2 .

It is a cyclic number.

It is not a de Polignac number, because 21455005105553 - 2³⁶ = 21386285628817 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 21455005105553.

It is not an unprimeable number, because it can be changed into a prime (21455005105253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175860697526 + ... + 175860697647.

It is an arithmetic number, because the mean of its divisors is an integer number (5451681625197).

Almost surely, 2^{21455005105553} is an apocalyptic number.

It is an amenable number.

21455005105553 is a deficient number, since it is larger than the sum of its proper divisors (351721395235).

21455005105553 is an equidigital number, since it uses as much as digits as its factorization.

21455005105553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 351721395234.

The product of its (nonzero) digits is 375000, while the sum is 41.

The spelling of 21455005105553 in words is "twenty-one trillion, four hundred fifty-five billion, five million, one hundred five thousand, five hundred fifty-three".