81691862336 has 168 divisors, whose sum is σ = 194083265376. Its totient is φ = 33997501440.

The previous prime is 81691862333. The next prime is 81691862347. The reversal of 81691862336 is 63326819618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81691862333) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 24405815 + ... + 24409161.

It is an arithmetic number, because the mean of its divisors is an integer number (1155257532).

Almost surely, 2^81691862336 is an apocalyptic number.

81691862336 is a gapful number since it is divisible by the number (86) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81691862336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97041632688).

81691862336 is an abundant number, since it is smaller than the sum of its proper divisors (112391403040).

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

81691862336 is a wasteful number, since it uses less digits than its factorization.

81691862336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3597 (or 3580 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 53.

The spelling of 81691862336 in words is "eighty-one billion, six hundred ninety-one million, eight hundred sixty-two thousand, three hundred thirty-six".