81551923200 has 1152 divisors, whose sum is σ = 339278284800. Its totient is φ = 19021824000.

The previous prime is 81551923151. The next prime is 81551923213. The reversal of 81551923200 is 232915518.

81551923200 is a `hidden beast` number, since 81 + 551 + 9 + 2 + 3 + 20 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 471398314 + ... + 471398486.

It is an arithmetic number, because the mean of its divisors is an integer number (294512400).

Almost surely, 2^81551923200 is an apocalyptic number.

81551923200 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 81551923200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (169639142400).

81551923200 is an abundant number, since it is smaller than the sum of its proper divisors (257726361600).

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

81551923200 is a wasteful number, since it uses less digits than its factorization.

81551923200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The spelling of 81551923200 in words is "eighty-one billion, five hundred fifty-one million, nine hundred twenty-three thousand, two hundred".