21688500265 has 8 divisors (see below), whose sum is σ = 26026990920. Its totient is φ = 17350273152.

The previous prime is 21688500259. The next prime is 21688500269. The reversal of 21688500265 is 56200588612.

It can be written as a sum of positive squares in 4 ways, for example, as 2894009616 + 18794490649 = 53796^2 + 137093^2 .

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 21688500265 - 2⁷ = 21688500137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21688500269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 287157 + ... + 354733.

It is an arithmetic number, because the mean of its divisors is an integer number (3253373865).

Almost surely, 2^21688500265 is an apocalyptic number.

It is an amenable number.

21688500265 is a deficient number, since it is larger than the sum of its proper divisors (4338490655).

21688500265 is an equidigital number, since it uses as much as digits as its factorization.

21688500265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131771.

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 21688500265 in words is "twenty-one billion, six hundred eighty-eight million, five hundred thousand, two hundred sixty-five".