265611391 has 2 divisors, whose sum is σ = 265611392. Its totient is φ = 265611390.

The previous prime is 265611389. The next prime is 265611397. The reversal of 265611391 is 193116562.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 265611391 - 2¹ = 265611389 is a prime.

It is a super-2 number, since 2×265611391² = 141098822057909762, which contains 22 as substring.

Together with 265611389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (265611397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 132805695 + 132805696.

It is an arithmetic number, because the mean of its divisors is an integer number (132805696).

Almost surely, 2^265611391 is an apocalyptic number.

265611391 is the 10308-th centered pentagonal number.

265611391 is a deficient number, since it is larger than the sum of its proper divisors (1).

265611391 is an equidigital number, since it uses as much as digits as its factorization.

265611391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9720, while the sum is 34.

The square root of 265611391 is about 16297.5885025976. The cubic root of 265611391 is about 642.8094194155.

The spelling of 265611391 in words is "two hundred sixty-five million, six hundred eleven thousand, three hundred ninety-one".