81279793646 has 16 divisors (see below), whose sum is σ = 123666805728. Its totient is φ = 40057802400.

The previous prime is 81279793619. The next prime is 81279793667. The reversal of 81279793646 is 64639797218.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 537896 + ... + 672228.

It is an arithmetic number, because the mean of its divisors is an integer number (7729175358).

Almost surely, 2^81279793646 is an apocalyptic number.

81279793646 is a deficient number, since it is larger than the sum of its proper divisors (42387012082).

81279793646 is a wasteful number, since it uses less digits than its factorization.

81279793646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138667.

The product of its digits is 27433728, while the sum is 62.

The spelling of 81279793646 in words is "eighty-one billion, two hundred seventy-nine million, seven hundred ninety-three thousand, six hundred forty-six".