21117357205 has 16 divisors (see below), whose sum is σ = 29005329024. Its totient is φ = 14458282560.

The previous prime is 21117357203. The next prime is 21117357221. The reversal of 21117357205 is 50275371112.

It is not a de Polignac number, because 21117357205 - 2¹ = 21117357203 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117357203) 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 15 ways as a sum of consecutive naturals, for example, 439131 + ... + 484840.

It is an arithmetic number, because the mean of its divisors is an integer number (1812833064).

Almost surely, 2^21117357205 is an apocalyptic number.

It is an amenable number.

21117357205 is a deficient number, since it is larger than the sum of its proper divisors (7887971819).

21117357205 is an equidigital number, since it uses as much as digits as its factorization.

21117357205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924636.

The product of its (nonzero) digits is 14700, while the sum is 34.

The spelling of 21117357205 in words is "twenty-one billion, one hundred seventeen million, three hundred fifty-seven thousand, two hundred five".