81165787200 has 504 divisors, whose sum is σ = 299794550016. Its totient is φ = 20805120000.

The previous prime is 81165787189. The next prime is 81165787229. The reversal of 81165787200 is 278756118.

It is a happy number.

81165787200 is a `hidden beast` number, since 8 + 1 + 1 + 6 + 578 + 72 + 0 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 77226675 + ... + 77227725.

Almost surely, 2^81165787200 is an apocalyptic number.

81165787200 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 81165787200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149897275008).

81165787200 is an abundant number, since it is smaller than the sum of its proper divisors (218628762816).

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

81165787200 is a wasteful number, since it uses less digits than its factorization.

81165787200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1283 (or 1265 counting only the distinct ones).

The product of its (nonzero) digits is 188160, while the sum is 45.

The spelling of 81165787200 in words is "eighty-one billion, one hundred sixty-five million, seven hundred eighty-seven thousand, two hundred".