81187814400 has 528 divisors, whose sum is σ = 334565610240. Its totient is φ = 16868966400.

The previous prime is 81187814399. The next prime is 81187814419. The reversal of 81187814400 is 441878118.

It is a tau number, because it is divible by the number of its divisors (528).

It is a super-2 number, since 2×81187814400² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5906736 + ... + 5920464.

Almost surely, 2^81187814400 is an apocalyptic number.

81187814400 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 81187814400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (167282805120).

81187814400 is an abundant number, since it is smaller than the sum of its proper divisors (253377795840).

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

81187814400 is a wasteful number, since it uses less digits than its factorization.

81187814400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13780 (or 13757 counting only the distinct ones).

The product of its (nonzero) digits is 57344, while the sum is 42.

The spelling of 81187814400 in words is "eighty-one billion, one hundred eighty-seven million, eight hundred fourteen thousand, four hundred".