81081644 has 12 divisors (see below), whose sum is σ = 162163344. Its totient is φ = 34749264.

The previous prime is 81081643. The next prime is 81081661. The reversal of 81081644 is 44618018.

81081644 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 81081644.

It is not an unprimeable number, because it can be changed into a prime (81081643) 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 in 3 ways as a sum of consecutive naturals, for example, 1447859 + ... + 1447914.

It is an arithmetic number, because the mean of its divisors is an integer number (13513612).

Almost surely, 2^81081644 is an apocalyptic number.

It is an amenable number.

81081644 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81081644 is a wasteful number, since it uses less digits than its factorization.

81081644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2895784 (or 2895782 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 81081644 is about 9004.5346353934. The cubic root of 81081644 is about 432.8201939115.

The spelling of 81081644 in words is "eighty-one million, eighty-one thousand, six hundred forty-four".