81384374681 has 4 divisors (see below), whose sum is σ = 81649470672. Its totient is φ = 81119278692.

The previous prime is 81384374677. The next prime is 81384374683. The reversal of 81384374681 is 18647348318.

It is a happy number.

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 81384374681 - 2² = 81384374677 is a prime.

It is a super-2 number, since 2×81384374681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81384374683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 132547535 + ... + 132548148.

It is an arithmetic number, because the mean of its divisors is an integer number (20412367668).

Almost surely, 2^81384374681 is an apocalyptic number.

It is an amenable number.

81384374681 is a deficient number, since it is larger than the sum of its proper divisors (265095991).

81384374681 is a wasteful number, since it uses less digits than its factorization.

81384374681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265095990.

The product of its digits is 3096576, while the sum is 53.

The spelling of 81384374681 in words is "eighty-one billion, three hundred eighty-four million, three hundred seventy-four thousand, six hundred eighty-one".