81771870128401 has 8 divisors (see below), whose sum is σ = 86637731599944. Its totient is φ = 76912203264000.

The previous prime is 81771870128393. The next prime is 81771870128449. The reversal of 81771870128401 is 10482107817718.

It is a Cunningham number, because it is equal to 9042780²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 8307514940176 + 73464355188225 = 2882276^2 + 8571135^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81771870128401 - 2³ = 81771870128393 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81771870128101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1548624600 + ... + 1548677401.

It is an arithmetic number, because the mean of its divisors is an integer number (10829716449993).

Almost surely, 2^{81771870128401} is an apocalyptic number.

It is an amenable number.

81771870128401 is a deficient number, since it is larger than the sum of its proper divisors (4865861471543).

81771870128401 is a wasteful number, since it uses less digits than its factorization.

81771870128401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3097303571.

The product of its (nonzero) digits is 1404928, while the sum is 55.

The spelling of 81771870128401 in words is "eighty-one trillion, seven hundred seventy-one billion, eight hundred seventy million, one hundred twenty-eight thousand, four hundred one".