81304272 has 120 divisors (see below), whose sum is σ = 263594240. Its totient is φ = 22913280.

The previous prime is 81304247. The next prime is 81304273. The reversal of 81304272 is 27240318.

It is a super-2 number, since 2×81304272² = 13220769290899968, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81304273) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 79122 + ... + 80142.

Almost surely, 2^81304272 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 81304272, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131797120).

81304272 is an abundant number, since it is smaller than the sum of its proper divisors (182289968).

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

81304272 is a wasteful number, since it uses less digits than its factorization.

81304272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1121 (or 1112 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 81304272 is about 9016.8881550122. Note that the first 3 decimals coincide. The cubic root of 81304272 is about 433.2159671629.

The spelling of 81304272 in words is "eighty-one million, three hundred four thousand, two hundred seventy-two".