81457777664 has 176 divisors, whose sum is σ = 176102263680. Its totient is φ = 37543772160.

The previous prime is 81457777663. The next prime is 81457777679. The reversal of 81457777664 is 46677775418.

It is a junction number, because it is equal to n+sod(n) for n = 81457777597 and 81457777606.

It is not an unprimeable number, because it can be changed into a prime (81457777663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 117883559 + ... + 117884249.

Almost surely, 2^81457777664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81457777664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88051131840).

81457777664 is an abundant number, since it is smaller than the sum of its proper divisors (94644486016).

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

81457777664 is a wasteful number, since it uses less digits than its factorization.

81457777664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 886 (or 868 counting only the distinct ones).

The product of its digits is 55319040, while the sum is 62.

The spelling of 81457777664 in words is "eighty-one billion, four hundred fifty-seven million, seven hundred seventy-seven thousand, six hundred sixty-four".