81997045200 has 1260 divisors, whose sum is σ = 361160252320. Its totient is φ = 17512796160.

The previous prime is 81997045189. The next prime is 81997045241. The reversal of 81997045200 is 254079918.

81997045200 is a `hidden beast` number, since 8 + 199 + 7 + 0 + 452 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1260).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 251 ways as a sum of consecutive naturals, for example, 589906731 + ... + 589906869.

Almost surely, 2^81997045200 is an apocalyptic number.

81997045200 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 81997045200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (180580126160).

81997045200 is an abundant number, since it is smaller than the sum of its proper divisors (279163207120).

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

81997045200 is a wasteful number, since it uses less digits than its factorization.

81997045200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The spelling of 81997045200 in words is "eighty-one billion, nine hundred ninety-seven million, forty-five thousand, two hundred".