81639107020800 has 576 divisors, whose sum is σ = 342714208636800. Its totient is φ = 18660365107200.

The previous prime is 81639107020769. The next prime is 81639107020811. The reversal of 81639107020800 is 802070193618.

81639107020800 is a `hidden beast` number, since 8 + 1 + 639 + 1 + 0 + 7 + 0 + 2 + 0 + 8 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (576).

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5458510 + ... + 13895090.

It is an arithmetic number, because the mean of its divisors is an integer number (594989945550).

Almost surely, 2^{81639107020800} is an apocalyptic number.

81639107020800 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 81639107020800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (171357104318400).

81639107020800 is an abundant number, since it is smaller than the sum of its proper divisors (261075101616000).

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

81639107020800 is a wasteful number, since it uses less digits than its factorization.

81639107020800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8436629 (or 8436598 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 81639107020800 in words is "eighty-one trillion, six hundred thirty-nine billion, one hundred seven million, twenty thousand, eight hundred".