81394557801 has 4 divisors (see below), whose sum is σ = 108526077072. Its totient is φ = 54263038532.

The previous prime is 81394557779. The next prime is 81394557817. The reversal of 81394557801 is 10875549318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81394557801 - 2⁹ = 81394557289 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81394557851) 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, 13565759631 + ... + 13565759636.

It is an arithmetic number, because the mean of its divisors is an integer number (27131519268).

Almost surely, 2^81394557801 is an apocalyptic number.

It is an amenable number.

81394557801 is a deficient number, since it is larger than the sum of its proper divisors (27131519271).

81394557801 is a wasteful number, since it uses less digits than its factorization.

81394557801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27131519270.

The product of its (nonzero) digits is 1209600, while the sum is 51.

The spelling of 81394557801 in words is "eighty-one billion, three hundred ninety-four million, five hundred fifty-seven thousand, eight hundred one".