81989444 has 12 divisors (see below), whose sum is σ = 144961404. Its totient is φ = 40571904.

The previous prime is 81989443. The next prime is 81989459. The reversal of 81989444 is 44498918.

It can be written as a sum of positive squares in 2 ways, for example, as 52417600 + 29571844 = 7240^2 + 5438^2 .

It is not an unprimeable number, because it can be changed into a prime (81989443) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105269 + ... + 106044.

It is an arithmetic number, because the mean of its divisors is an integer number (12080117).

Almost surely, 2^81989444 is an apocalyptic number.

It is an amenable number.

81989444 is a deficient number, since it is larger than the sum of its proper divisors (62971960).

81989444 is a wasteful number, since it uses less digits than its factorization.

81989444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211414 (or 211412 counting only the distinct ones).

The product of its digits is 331776, while the sum is 47.

The square root of 81989444 is about 9054.8022617835. The cubic root of 81989444 is about 434.4295053595.

The spelling of 81989444 in words is "eighty-one million, nine hundred eighty-nine thousand, four hundred forty-four".