81306872 has 8 divisors (see below), whose sum is σ = 152450400. Its totient is φ = 40653432.

The previous prime is 81306859. The next prime is 81306877. The reversal of 81306872 is 27860318.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×81306872² = 13221614868848768, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81306877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5081672 + ... + 5081687.

It is an arithmetic number, because the mean of its divisors is an integer number (19056300).

Almost surely, 2^81306872 is an apocalyptic number.

It is an amenable number.

81306872 is a deficient number, since it is larger than the sum of its proper divisors (71143528).

81306872 is a wasteful number, since it uses less digits than its factorization.

81306872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10163365 (or 10163361 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 81306872 is about 9017.0323277673. The cubic root of 81306872 is about 433.2205849994.

The spelling of 81306872 in words is "eighty-one million, three hundred six thousand, eight hundred seventy-two".