81273312 has 144 divisors (see below), whose sum is σ = 246486240. Its totient is φ = 25353216.

The previous prime is 81273307. The next prime is 81273331. The reversal of 81273312 is 21337218.

81273312 is a `hidden beast` number, since 81 + 273 + 312 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 308893 + ... + 309155.

It is an arithmetic number, because the mean of its divisors is an integer number (1711710).

Almost surely, 2^81273312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81273312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123243120).

81273312 is an abundant number, since it is smaller than the sum of its proper divisors (165212928).

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

81273312 is a wasteful number, since it uses less digits than its factorization.

81273312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 345 (or 334 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 81273312 is about 9015.1712130164. The cubic root of 81273312 is about 433.1609718192.

The spelling of 81273312 in words is "eighty-one million, two hundred seventy-three thousand, three hundred twelve".