81165437640000 has 700 divisors, whose sum is σ = 343604084671584. Its totient is φ = 18552094848000.

The previous prime is 81165437639977. The next prime is 81165437640017. The reversal of 81165437640000 is 4673456118.

81165437640000 is a `hidden beast` number, since 81 + 1 + 65 + 43 + 76 + 400 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (700).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 99 ways as a sum of consecutive naturals, for example, 20890639 + ... + 24469361.

Almost surely, 2^{81165437640000} is an apocalyptic number.

81165437640000 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 81165437640000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (171802042335792).

81165437640000 is an abundant number, since it is smaller than the sum of its proper divisors (262438647031584).

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

81165437640000 is an equidigital number, since it uses as much as digits as its factorization.

81165437640000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3578774 (or 3578740 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 81165437640000 in words is "eighty-one trillion, one hundred sixty-five billion, four hundred thirty-seven million, six hundred forty thousand".