21650065205 has 4 divisors (see below), whose sum is σ = 25980078252. Its totient is φ = 17320052160.

The previous prime is 21650065187. The next prime is 21650065207. The reversal of 21650065205 is 50256005612.

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 14916713956 + 6733351249 = 122134^2 + 82057^2 .

It is not a de Polignac number, because 21650065205 - 2⁸ = 21650064949 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 (21650065207) 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 3 ways as a sum of consecutive naturals, for example, 2165006516 + ... + 2165006525.

It is an arithmetic number, because the mean of its divisors is an integer number (6495019563).

Almost surely, 2^21650065205 is an apocalyptic number.

It is an amenable number.

21650065205 is a deficient number, since it is larger than the sum of its proper divisors (4330013047).

21650065205 is an equidigital number, since it uses as much as digits as its factorization.

21650065205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4330013046.

The product of its (nonzero) digits is 18000, while the sum is 32.

The spelling of 21650065205 in words is "twenty-one billion, six hundred fifty million, sixty-five thousand, two hundred five".