81338897764891 has 8 divisors (see below), whose sum is σ = 87709055258160. Its totient is φ = 74984928729312.

The previous prime is 81338897764853. The next prime is 81338897764907. The reversal of 81338897764891 is 19846779883318.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81338897764891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81338897764801) 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, 4047103981 + ... + 4047124078.

It is an arithmetic number, because the mean of its divisors is an integer number (10963631907270).

Almost surely, 2^{81338897764891} is an apocalyptic number.

81338897764891 is a deficient number, since it is larger than the sum of its proper divisors (6370157493269).

81338897764891 is a wasteful number, since it uses less digits than its factorization.

81338897764891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8094228845.

The product of its digits is 3511517184, while the sum is 82.

The spelling of 81338897764891 in words is "eighty-one trillion, three hundred thirty-eight billion, eight hundred ninety-seven million, seven hundred sixty-four thousand, eight hundred ninety-one".