21171361205 has 8 divisors (see below), whose sum is σ = 25500079800. Its totient is φ = 16874124736.

The previous prime is 21171361199. The next prime is 21171361297. The reversal of 21171361205 is 50216317112.

It can be written as a sum of positive squares in 4 ways, for example, as 78446449 + 21092914756 = 8857^2 + 145234^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21171361205 - 2⁸ = 21171360949 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7869050 + ... + 7871739.

It is an arithmetic number, because the mean of its divisors is an integer number (3187509975).

Almost surely, 2^21171361205 is an apocalyptic number.

It is an amenable number.

21171361205 is a deficient number, since it is larger than the sum of its proper divisors (4328718595).

21171361205 is a wasteful number, since it uses less digits than its factorization.

21171361205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15741063.

The product of its (nonzero) digits is 2520, while the sum is 29.

Adding to 21171361205 its reverse (50216317112), we get a palindrome (71387678317).

The spelling of 21171361205 in words is "twenty-one billion, one hundred seventy-one million, three hundred sixty-one thousand, two hundred five".