81373982639040 has 1344 divisors, whose sum is σ = 366934378696704. Its totient is φ = 16062166204416.

The previous prime is 81373982639009. The next prime is 81373982639099. The reversal of 81373982639040 is 4093628937318.

81373982639040 is a `hidden beast` number, since 8 + 1 + 373 + 9 + 82 + 63 + 90 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (1344).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 743990437 + ... + 744099803.

It is an arithmetic number, because the mean of its divisors is an integer number (273016650816).

Almost surely, 2^{81373982639040} is an apocalyptic number.

81373982639040 is a gapful number since it is divisible by the number (80) 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 81373982639040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (183467189348352).

81373982639040 is an abundant number, since it is smaller than the sum of its proper divisors (285560396057664).

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

81373982639040 is a wasteful number, since it uses less digits than its factorization.

81373982639040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109594 (or 109581 counting only the distinct ones).

The product of its (nonzero) digits is 47029248, while the sum is 63.

The spelling of 81373982639040 in words is "eighty-one trillion, three hundred seventy-three billion, nine hundred eighty-two million, six hundred thirty-nine thousand, forty".