265681099921 has 2 divisors, whose sum is σ = 265681099922. Its totient is φ = 265681099920.

The previous prime is 265681099919. The next prime is 265681099939. The reversal of 265681099921 is 129990186562.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 192383118225 + 73297981696 = 438615^2 + 270736^2 .

It is a cyclic number.

It is not a de Polignac number, because 265681099921 - 2¹ = 265681099919 is a prime.

Together with 265681099919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (265681099951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 132840549960 + 132840549961.

It is an arithmetic number, because the mean of its divisors is an integer number (132840549961).

Almost surely, 2^265681099921 is an apocalyptic number.

It is an amenable number.

265681099921 is a deficient number, since it is larger than the sum of its proper divisors (1).

265681099921 is an equidigital number, since it uses as much as digits as its factorization.

265681099921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4199040, while the sum is 58.

The spelling of 265681099921 in words is "two hundred sixty-five billion, six hundred eighty-one million, ninety-nine thousand, nine hundred twenty-one".