81738642177 has 6 divisors (see below), whose sum is σ = 118066927602. Its totient is φ = 54492428112.

The previous prime is 81738642169. The next prime is 81738642197. The reversal of 81738642177 is 77124683718.

81738642177 is a `hidden beast` number, since 8 + 1 + 73 + 86 + 421 + 77 = 666.

It can be written as a sum of positive squares in only one way, i.e., 49889242881 + 31849399296 = 223359^2 + 178464^2 .

It is not a de Polignac number, because 81738642177 - 2³ = 81738642169 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81738642137) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4541035668 + ... + 4541035685.

It is an arithmetic number, because the mean of its divisors is an integer number (19677821267).

Almost surely, 2^81738642177 is an apocalyptic number.

It is an amenable number.

81738642177 is a deficient number, since it is larger than the sum of its proper divisors (36328285425).

81738642177 is a wasteful number, since it uses less digits than its factorization.

81738642177 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9082071359 (or 9082071356 counting only the distinct ones).

The product of its digits is 3161088, while the sum is 54.

The spelling of 81738642177 in words is "eighty-one billion, seven hundred thirty-eight million, six hundred forty-two thousand, one hundred seventy-seven".