21173232305 has 4 divisors (see below), whose sum is σ = 25407878772. Its totient is φ = 16938585840.

The previous prime is 21173232251. The next prime is 21173232313. The reversal of 21173232305 is 50323237112.

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 5647823104 + 15525409201 = 75152^2 + 124601^2 .

It is not a de Polignac number, because 21173232305 - 2²⁸ = 20904796849 is a prime.

It is a super-2 number, since 2×21173232305² (a number of 21 digits) contains 22 as substring.

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, 2117323226 + ... + 2117323235.

It is an arithmetic number, because the mean of its divisors is an integer number (6351969693).

Almost surely, 2^21173232305 is an apocalyptic number.

It is an amenable number.

21173232305 is a deficient number, since it is larger than the sum of its proper divisors (4234646467).

21173232305 is an equidigital number, since it uses as much as digits as its factorization.

21173232305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4234646466.

The product of its (nonzero) digits is 7560, while the sum is 29.

Adding to 21173232305 its reverse (50323237112), we get a palindrome (71496469417).

The spelling of 21173232305 in words is "twenty-one billion, one hundred seventy-three million, two hundred thirty-two thousand, three hundred five".