81265766400 has 2496 divisors, whose sum is σ = 409523788800. Its totient is φ = 15288238080.

The previous prime is 81265766363. The next prime is 81265766401. The reversal of 81265766400 is 466756218.

81265766400 is a `hidden beast` number, since 8 + 12 + 6 + 576 + 64 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (2496).

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

It is not an unprimeable number, because it can be changed into a prime (81265766401) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 4277145591 + ... + 4277145609.

Almost surely, 2^81265766400 is an apocalyptic number.

81265766400 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 81265766400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (204761894400).

81265766400 is an abundant number, since it is smaller than the sum of its proper divisors (328258022400).

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

81265766400 is a wasteful number, since it uses less digits than its factorization.

81265766400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99 (or 66 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 81265766400 in words is "eighty-one billion, two hundred sixty-five million, seven hundred sixty-six thousand, four hundred".