81575444 has 6 divisors (see below), whose sum is σ = 142757034. Its totient is φ = 40787720.

The previous prime is 81575443. The next prime is 81575447. The reversal of 81575444 is 44457518.

It can be written as a sum of positive squares in only one way, i.e., 79210000 + 2365444 = 8900^2 + 1538^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81575398 and 81575407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81575443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10196927 + ... + 10196934.

It is an arithmetic number, because the mean of its divisors is an integer number (23792839).

Almost surely, 2^81575444 is an apocalyptic number.

It is an amenable number.

81575444 is a deficient number, since it is larger than the sum of its proper divisors (61181590).

81575444 is a wasteful number, since it uses less digits than its factorization.

81575444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20393865 (or 20393863 counting only the distinct ones).

The product of its digits is 89600, while the sum is 38.

The square root of 81575444 is about 9031.9125327917. The cubic root of 81575444 is about 433.6970639692.

The spelling of 81575444 in words is "eighty-one million, five hundred seventy-five thousand, four hundred forty-four".