21255536655445 has 4 divisors (see below), whose sum is σ = 25506643986540. Its totient is φ = 17004429324352.

The previous prime is 21255536655439. The next prime is 21255536655527. The reversal of 21255536655445 is 54455663555212.

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 15486499513521 + 5769037141924 = 3935289^2 + 2401882^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255536655445 - 2²³ = 21255528266837 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21255536655445.

It is a congruent number.

It is an unprimeable number.

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, 2125553665540 + ... + 2125553665549.

It is an arithmetic number, because the mean of its divisors is an integer number (6376660996635).

Almost surely, 2^{21255536655445} is an apocalyptic number.

It is an amenable number.

21255536655445 is a deficient number, since it is larger than the sum of its proper divisors (4251107331095).

21255536655445 is an equidigital number, since it uses as much as digits as its factorization.

21255536655445 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4251107331094.

The product of its digits is 108000000, while the sum is 58.

The spelling of 21255536655445 in words is "twenty-one trillion, two hundred fifty-five billion, five hundred thirty-six million, six hundred fifty-five thousand, four hundred forty-five".