21444051511555 has 4 divisors (see below), whose sum is σ = 25732861813872. Its totient is φ = 17155241209240.

The previous prime is 21444051511517. The next prime is 21444051511579. The reversal of 21444051511555 is 55511515044412.

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

It is not a de Polignac number, because 21444051511555 - 2²⁵ = 21444017957123 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2144405151151 + ... + 2144405151160.

It is an arithmetic number, because the mean of its divisors is an integer number (6433215453468).

Almost surely, 2^{21444051511555} is an apocalyptic number.

21444051511555 is a deficient number, since it is larger than the sum of its proper divisors (4288810302317).

21444051511555 is an equidigital number, since it uses as much as digits as its factorization.

21444051511555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4288810302316.

The product of its (nonzero) digits is 400000, while the sum is 43.

Adding to 21444051511555 its reverse (55511515044412), we get a palindrome (76955566555967).

The spelling of 21444051511555 in words is "twenty-one trillion, four hundred forty-four billion, fifty-one million, five hundred eleven thousand, five hundred fifty-five".