81812159936640 has 3072 divisors, whose sum is σ = 364618108108800. Its totient is φ = 16482631680000.

The previous prime is 81812159936603. The next prime is 81812159936677. The reversal of 81812159936640 is 4663995121818.

81812159936640 is a `hidden beast` number, since 8 + 1 + 8 + 1 + 2 + 1 + 599 + 36 + 6 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (81812159936603) and next prime (81812159936677).

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

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 71079200065 + ... + 71079201215.

It is an arithmetic number, because the mean of its divisors is an integer number (118690790400).

Almost surely, 2^{81812159936640} is an apocalyptic number.

81812159936640 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 81812159936640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (182309054054400).

81812159936640 is an abundant number, since it is smaller than the sum of its proper divisors (282805948172160).

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

81812159936640 is a wasteful number, since it uses less digits than its factorization.

81812159936640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1347 (or 1332 counting only the distinct ones).

The product of its (nonzero) digits is 22394880, while the sum is 63.

The spelling of 81812159936640 in words is "eighty-one trillion, eight hundred twelve billion, one hundred fifty-nine million, nine hundred thirty-six thousand, six hundred forty".