855566665531 has 2 divisors, whose sum is σ = 855566665532. Its totient is φ = 855566665530.

The previous prime is 855566665529. The next prime is 855566665559. The reversal of 855566665531 is 135566665558.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 855566665531 - 2¹ = 855566665529 is a prime.

It is a super-3 number, since 3×855566665531³ (a number of 37 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 855566665529, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 855566665531.

It is not a weakly prime, because it can be changed into another prime (855566665231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 427783332765 + 427783332766.

It is an arithmetic number, because the mean of its divisors is an integer number (427783332766).

Almost surely, 2^855566665531 is an apocalyptic number.

855566665531 is a deficient number, since it is larger than the sum of its proper divisors (1).

855566665531 is an equidigital number, since it uses as much as digits as its factorization.

855566665531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 97200000, while the sum is 61.

The spelling of 855566665531 in words is "eight hundred fifty-five billion, five hundred sixty-six million, six hundred sixty-five thousand, five hundred thirty-one".