81185475823 has 2 divisors, whose sum is σ = 81185475824. Its totient is φ = 81185475822.

The previous prime is 81185475817. The next prime is 81185475857. The reversal of 81185475823 is 32857458118.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81185475823 - 2³³ = 72595541231 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81185475223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40592737911 + 40592737912.

It is an arithmetic number, because the mean of its divisors is an integer number (40592737912).

Almost surely, 2^81185475823 is an apocalyptic number.

81185475823 is a deficient number, since it is larger than the sum of its proper divisors (1).

81185475823 is an equidigital number, since it uses as much as digits as its factorization.

81185475823 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2150400, while the sum is 52.

The spelling of 81185475823 in words is "eighty-one billion, one hundred eighty-five million, four hundred seventy-five thousand, eight hundred twenty-three".