81775810141 has 4 divisors (see below), whose sum is σ = 86586151932. Its totient is φ = 76965468352.

The previous prime is 81775810139. The next prime is 81775810189. The reversal of 81775810141 is 14101857718.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 36317306041 + 45458504100 = 190571^2 + 213210^2 .

It is a cyclic number.

It is not a de Polignac number, because 81775810141 - 2¹ = 81775810139 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81775819141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2405170870 + ... + 2405170903.

It is an arithmetic number, because the mean of its divisors is an integer number (21646537983).

Almost surely, 2^81775810141 is an apocalyptic number.

It is an amenable number.

81775810141 is a deficient number, since it is larger than the sum of its proper divisors (4810341791).

81775810141 is a wasteful number, since it uses less digits than its factorization.

81775810141 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4810341790.

The product of its (nonzero) digits is 62720, while the sum is 43.

The spelling of 81775810141 in words is "eighty-one billion, seven hundred seventy-five million, eight hundred ten thousand, one hundred forty-one".