81808056 has 160 divisors (see below), whose sum is σ = 261360000. Its totient is φ = 23664960.

The previous prime is 81808049. The next prime is 81808057. The reversal of 81808056 is 65080818.

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

It is a self number, because there is not a number n which added to its sum of digits gives 81808056.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81808057) 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 39 ways as a sum of consecutive naturals, for example, 163695 + ... + 164193.

It is an arithmetic number, because the mean of its divisors is an integer number (1633500).

Almost surely, 2^81808056 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 81808056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130680000).

81808056 is an abundant number, since it is smaller than the sum of its proper divisors (179551944).

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

81808056 is a wasteful number, since it uses less digits than its factorization.

81808056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 551 (or 538 counting only the distinct ones).

The product of its (nonzero) digits is 15360, while the sum is 36.

The square root of 81808056 is about 9044.7805943539. The cubic root of 81808056 is about 434.1089011547.

The spelling of 81808056 in words is "eighty-one million, eight hundred eight thousand, fifty-six".