81664404486 has 64 divisors (see below), whose sum is σ = 195496574976. Its totient is φ = 22235796000.

The previous prime is 81664404473. The next prime is 81664404511. The reversal of 81664404486 is 68440446618.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 105811 + ... + 417761.

It is an arithmetic number, because the mean of its divisors is an integer number (3054633984).

Almost surely, 2^81664404486 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81664404486, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97748287488).

81664404486 is an abundant number, since it is smaller than the sum of its proper divisors (113832170490).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81664404486 is a wasteful number, since it uses less digits than its factorization.

81664404486 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312257.

The product of its (nonzero) digits is 3538944, while the sum is 51.

The spelling of 81664404486 in words is "eighty-one billion, six hundred sixty-four million, four hundred four thousand, four hundred eighty-six".