21110055503 has 4 divisors (see below), whose sum is σ = 21182103768. Its totient is φ = 21038007240.

The previous prime is 21110055493. The next prime is 21110055581. The reversal of 21110055503 is 30555001112.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21110055503 - 2⁴ = 21110055487 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21110052503) by changing a digit.

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, 36023693 + ... + 36024278.

It is an arithmetic number, because the mean of its divisors is an integer number (5295525942).

Almost surely, 2^21110055503 is an apocalyptic number.

21110055503 is a deficient number, since it is larger than the sum of its proper divisors (72048265).

21110055503 is an equidigital number, since it uses as much as digits as its factorization.

21110055503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72048264.

The product of its (nonzero) digits is 750, while the sum is 23.

Adding to 21110055503 its reverse (30555001112), we get a palindrome (51665056615).

The spelling of 21110055503 in words is "twenty-one billion, one hundred ten million, fifty-five thousand, five hundred three".