81375778841 has 16 divisors (see below), whose sum is σ = 93919651200. Its totient is φ = 69064783488.

The previous prime is 81375778807. The next prime is 81375778849. The reversal of 81375778841 is 14887757318.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81375778841 - 2¹⁸ = 81375516697 is a prime.

It is a Smith number, since the sum of its digits (59) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81375778849) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 174365 + ... + 439493.

It is an arithmetic number, because the mean of its divisors is an integer number (5869978200).

Almost surely, 2^81375778841 is an apocalyptic number.

It is an amenable number.

81375778841 is a deficient number, since it is larger than the sum of its proper divisors (12543872359).

81375778841 is a wasteful number, since it uses less digits than its factorization.

81375778841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265568.

The product of its digits is 10536960, while the sum is 59.

It can be divided in two parts, 8137577 and 8841, that added together give a palindrome (8146418).

The spelling of 81375778841 in words is "eighty-one billion, three hundred seventy-five million, seven hundred seventy-eight thousand, eight hundred forty-one".