81657977385600 has 4032 divisors, whose sum is σ = 388207728427680. Its totient is φ = 16773765120000.

The previous prime is 81657977385583. The next prime is 81657977385641. The reversal of 81657977385600 is 658377975618.

81657977385600 is a `hidden beast` number, since 8 + 1 + 6 + 5 + 7 + 9 + 7 + 7 + 3 + 8 + 5 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (4032).

It is a super-2 number, since 2×81657977385600² (a number of 29 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (72).

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 503 ways as a sum of consecutive naturals, for example, 126995298879 + ... + 126995299521.

Almost surely, 2^{81657977385600} is an apocalyptic number.

81657977385600 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 81657977385600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (194103864213840).

81657977385600 is an abundant number, since it is smaller than the sum of its proper divisors (306549751042080).

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

81657977385600 is a wasteful number, since it uses less digits than its factorization.

81657977385600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 811 (or 772 counting only the distinct ones).

The product of its (nonzero) digits is 533433600, while the sum is 72.

The spelling of 81657977385600 in words is "eighty-one trillion, six hundred fifty-seven billion, nine hundred seventy-seven million, three hundred eighty-five thousand, six hundred".