21505200013103 has 4 divisors (see below), whose sum is σ = 21530293596240. Its totient is φ = 21480106429968.

The previous prime is 21505200013067. The next prime is 21505200013117. The reversal of 21505200013103 is 30131000250512.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21505200013103 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 (21505200013123) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12546790283 + ... + 12546791996.

It is an arithmetic number, because the mean of its divisors is an integer number (5382573399060).

Almost surely, 2^{21505200013103} is an apocalyptic number.

21505200013103 is a deficient number, since it is larger than the sum of its proper divisors (25093583137).

21505200013103 is an equidigital number, since it uses as much as digits as its factorization.

21505200013103 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25093583136.

The product of its (nonzero) digits is 900, while the sum is 23.

Adding to 21505200013103 its reverse (30131000250512), we get a palindrome (51636200263615).

The spelling of 21505200013103 in words is "twenty-one trillion, five hundred five billion, two hundred million, thirteen thousand, one hundred three".