21203116265 has 4 divisors (see below), whose sum is σ = 25443739524. Its totient is φ = 16962493008.

The previous prime is 21203116247. The next prime is 21203116271. The reversal of 21203116265 is 56261130212.

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 5289798361 + 15913317904 = 72731^2 + 126148^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203116265 - 2⁶ = 21203116201 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2120311622 + ... + 2120311631.

It is an arithmetic number, because the mean of its divisors is an integer number (6360934881).

Almost surely, 2^21203116265 is an apocalyptic number.

It is an amenable number.

21203116265 is a deficient number, since it is larger than the sum of its proper divisors (4240623259).

21203116265 is an equidigital number, since it uses as much as digits as its factorization.

21203116265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4240623258.

The product of its (nonzero) digits is 4320, while the sum is 29.

Adding to 21203116265 its reverse (56261130212), we get a palindrome (77464246477).

The spelling of 21203116265 in words is "twenty-one billion, two hundred three million, one hundred sixteen thousand, two hundred sixty-five".