81817478400 has 432 divisors, whose sum is σ = 316947741824. Its totient is φ = 18194595840.

The previous prime is 81817478389. The next prime is 81817478401. The reversal of 81817478400 is 487471818.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 81817478400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81817478401) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4964574 + ... + 4981026.

Almost surely, 2^81817478400 is an apocalyptic number.

81817478400 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 81817478400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158473870912).

81817478400 is an abundant number, since it is smaller than the sum of its proper divisors (235130263424).

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

81817478400 is a wasteful number, since it uses less digits than its factorization.

81817478400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16526 (or 16507 counting only the distinct ones).

The product of its (nonzero) digits is 401408, while the sum is 48.

The spelling of 81817478400 in words is "eighty-one billion, eight hundred seventeen million, four hundred seventy-eight thousand, four hundred".