81296400 has 120 divisors (see below), whose sum is σ = 267603904. Its totient is φ = 21081600.

The previous prime is 81296387. The next prime is 81296407. The reversal of 81296400 is 469218.

It is a tau number, because it is divible by the number of its divisors (120).

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

It is not an unprimeable number, because it can be changed into a prime (81296407) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 43485 + ... + 45315.

Almost surely, 2^81296400 is an apocalyptic number.

81296400 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 81296400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133801952).

81296400 is an abundant number, since it is smaller than the sum of its proper divisors (186307504).

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

81296400 is a wasteful number, since it uses less digits than its factorization.

81296400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1889 (or 1878 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 81296400 is about 9016.4516302146. The cubic root of 81296400 is about 433.2019851745.

The spelling of 81296400 in words is "eighty-one million, two hundred ninety-six thousand, four hundred".