81781560000 has 1680 divisors, whose sum is σ = 374326977024. Its totient is φ = 16625664000.

The previous prime is 81781559999. The next prime is 81781560011. The reversal of 81781560000 is 6518718.

81781560000 is a `hidden beast` number, since 8 + 17 + 81 + 560 + 0 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1680).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 985319959 + ... + 985320041.

Almost surely, 2^81781560000 is an apocalyptic number.

81781560000 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 81781560000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (187163488512).

81781560000 is an abundant number, since it is smaller than the sum of its proper divisors (292545417024).

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

81781560000 is a wasteful number, since it uses less digits than its factorization.

81781560000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168 (or 140 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 36.

The spelling of 81781560000 in words is "eighty-one billion, seven hundred eighty-one million, five hundred sixty thousand".