81378144681 has 8 divisors (see below), whose sum is σ = 108711660000. Its totient is φ = 54148362912.

The previous prime is 81378144667. The next prime is 81378144691. The reversal of 81378144681 is 18644187318.

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

It is not a de Polignac number, because 81378144681 - 2²³ = 81369756073 is a prime.

It is a super-2 number, since 2×81378144681² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81378144691) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25931556 + ... + 25934693.

It is an arithmetic number, because the mean of its divisors is an integer number (13588957500).

Almost surely, 2^81378144681 is an apocalyptic number.

It is an amenable number.

81378144681 is a deficient number, since it is larger than the sum of its proper divisors (27333515319).

81378144681 is a wasteful number, since it uses less digits than its factorization.

81378144681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51866775.

The product of its digits is 1032192, while the sum is 51.

The spelling of 81378144681 in words is "eighty-one billion, three hundred seventy-eight million, one hundred forty-four thousand, six hundred eighty-one".