81856678641 has 8 divisors (see below), whose sum is σ = 109180054464. Its totient is φ = 54552210960.

The previous prime is 81856678609. The next prime is 81856678663. The reversal of 81856678641 is 14687665818.

It is a happy number.

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

It is not a de Polignac number, because 81856678641 - 2⁵ = 81856678609 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81856678601) 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, 4716930 + ... + 4734251.

It is an arithmetic number, because the mean of its divisors is an integer number (13647506808).

Almost surely, 2^81856678641 is an apocalyptic number.

It is an amenable number.

81856678641 is a deficient number, since it is larger than the sum of its proper divisors (27323375823).

81856678641 is a wasteful number, since it uses less digits than its factorization.

81856678641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9454071.

The product of its digits is 15482880, while the sum is 60.

The spelling of 81856678641 in words is "eighty-one billion, eight hundred fifty-six million, six hundred seventy-eight thousand, six hundred forty-one".