81421799659200 has 9072 divisors, whose sum is σ = 437687169978240. Its totient is φ = 14795401420800.

The previous prime is 81421799659177. The next prime is 81421799659247. The reversal of 81421799659200 is 295699712418.

81421799659200 is a `hidden beast` number, since 8 + 1 + 421 + 79 + 96 + 59 + 2 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (9072).

It is a super-2 number, since 2×81421799659200² (a number of 29 digits) contains 22 as substring.

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 1295 ways as a sum of consecutive naturals, for example, 4285357876791 + ... + 4285357876809.

Almost surely, 2^{81421799659200} is an apocalyptic number.

81421799659200 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 81421799659200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (218843584989120).

81421799659200 is an abundant number, since it is smaller than the sum of its proper divisors (356265370319040).

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

81421799659200 is a wasteful number, since it uses less digits than its factorization.

81421799659200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129 (or 60 counting only the distinct ones).

The product of its (nonzero) digits is 19595520, while the sum is 63.

The spelling of 81421799659200 in words is "eighty-one trillion, four hundred twenty-one billion, seven hundred ninety-nine million, six hundred fifty-nine thousand, two hundred".