81355686336 has 448 divisors, whose sum is σ = 260968296960. Its totient is φ = 24757125120.

The previous prime is 81355686331. The next prime is 81355686341. The reversal of 81355686336 is 63368655318.

81355686336 is a `hidden beast` number, since 8 + 1 + 3 + 556 + 86 + 3 + 3 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (81355686331) and next prime (81355686341).

It is a Harshad number since it is a multiple of its sum of digits (54).

Its product of digits (9331200) is a multiple of the sum of its prime factors (729).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81355686331) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 148730415 + ... + 148730961.

It is an arithmetic number, because the mean of its divisors is an integer number (582518520).

Almost surely, 2^81355686336 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 81355686336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130484148480).

81355686336 is an abundant number, since it is smaller than the sum of its proper divisors (179612610624).

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

81355686336 is a wasteful number, since it uses less digits than its factorization.

81355686336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729 (or 713 counting only the distinct ones).

The product of its digits is 9331200, while the sum is 54.

The spelling of 81355686336 in words is "eighty-one billion, three hundred fifty-five million, six hundred eighty-six thousand, three hundred thirty-six".