81761613373440 has 3360 divisors, whose sum is σ = 400691402917344. Its totient is φ = 15678088151040.

The previous prime is 81761613373369. The next prime is 81761613373471. The reversal of 81761613373440 is 4437331616718.

81761613373440 is a `hidden beast` number, since 8 + 1 + 7 + 6 + 161 + 3 + 37 + 3 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (3360).

It is a super-2 number, since 2×81761613373440² (a number of 29 digits) contains 22 as substring.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 23247542562 + ... + 23247546078.

Almost surely, 2^{81761613373440} is an apocalyptic number.

81761613373440 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 81761613373440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (200345701458672).

81761613373440 is an abundant number, since it is smaller than the sum of its proper divisors (318929789543904).

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

81761613373440 is a wasteful number, since it uses less digits than its factorization.

81761613373440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3598 (or 3558 counting only the distinct ones).

The product of its (nonzero) digits is 6096384, while the sum is 54.

The spelling of 81761613373440 in words is "eighty-one trillion, seven hundred sixty-one billion, six hundred thirteen million, three hundred seventy-three thousand, four hundred forty".