21045115205 has 8 divisors (see below), whose sum is σ = 25276048152. Its totient is φ = 16821485568.

The previous prime is 21045115193. The next prime is 21045115219. The reversal of 21045115205 is 50251154012.

It can be written as a sum of positive squares in 4 ways, for example, as 10535174881 + 10509940324 = 102641^2 + 102518^2 .

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 21045115205 - 2⁸ = 21045114949 is a prime.

It is a Duffinian number.

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, 1819484 + ... + 1831013.

It is an arithmetic number, because the mean of its divisors is an integer number (3159506019).

Almost surely, 2^21045115205 is an apocalyptic number.

It is an amenable number.

21045115205 is a deficient number, since it is larger than the sum of its proper divisors (4230932947).

21045115205 is a wasteful number, since it uses less digits than its factorization.

21045115205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3651655.

The product of its (nonzero) digits is 2000, while the sum is 26.

Adding to 21045115205 its reverse (50251154012), we get a palindrome (71296269217).

The spelling of 21045115205 in words is "twenty-one billion, forty-five million, one hundred fifteen thousand, two hundred five".