81408672 has 96 divisors (see below), whose sum is σ = 241617600. Its totient is φ = 26659584.

The previous prime is 81408643. The next prime is 81408737. The reversal of 81408672 is 27680418.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

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 15 ways as a sum of consecutive naturals, for example, 50178 + ... + 51774.

It is an arithmetic number, because the mean of its divisors is an integer number (2516850).

Almost surely, 2^81408672 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 81408672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120808800).

81408672 is an abundant number, since it is smaller than the sum of its proper divisors (160208928).

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

81408672 is a wasteful number, since it uses less digits than its factorization.

81408672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1675 (or 1661 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 81408672 is about 9022.6754347034. The cubic root of 81408672 is about 433.4013137267.

The spelling of 81408672 in words is "eighty-one million, four hundred eight thousand, six hundred seventy-two".