81685444 has 9 divisors (see below), whose sum is σ = 142981167. Its totient is φ = 40833684.

The previous prime is 81685421. The next prime is 81685451. The reversal of 81685444 is 44458618.

The square root of 81685444 is 9038.

It is a perfect power (a square), and thus also a powerful number.

It is a super-2 number, since 2×81685444² = 13345023522954272, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81685397 and 81685406.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 15817 + ... + 20335.

Almost surely, 2^81685444 is an apocalyptic number.

81685444 is the 9038-th square number.

It is an amenable number.

81685444 is a deficient number, since it is larger than the sum of its proper divisors (61295723).

81685444 is an frugal number, since it uses more digits than its factorization.

81685444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9042 (or 4521 counting only the distinct ones).

The product of its digits is 122880, while the sum is 40.

The cubic root of 81685444 is about 433.8919152932.

The spelling of 81685444 in words is "eighty-one million, six hundred eighty-five thousand, four hundred forty-four".