81278400 has 336 divisors, whose sum is σ = 317479680. Its totient is φ = 17817600.

The previous prime is 81278383. The next prime is 81278423. The reversal of 81278400 is 487218.

It is a tau number, because it is divible by the number of its divisors (336).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1377571 + ... + 1377629.

It is an arithmetic number, because the mean of its divisors is an integer number (944880).

Almost surely, 2^81278400 is an apocalyptic number.

81278400 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 81278400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158739840).

81278400 is an abundant number, since it is smaller than the sum of its proper divisors (236201280).

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

81278400 is a wasteful number, since it uses less digits than its factorization.

81278400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132 (or 117 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 81278400 is about 9015.4533995801. The cubic root of 81278400 is about 433.1700107726.

The spelling of 81278400 in words is "eighty-one million, two hundred seventy-eight thousand, four hundred".