81786244 has 6 divisors (see below), whose sum is σ = 143125934. Its totient is φ = 40893120.

The previous prime is 81786233. The next prime is 81786247. The reversal of 81786244 is 44268718.

It can be written as a sum of positive squares in only one way, i.e., 65286400 + 16499844 = 8080^2 + 4062^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81786197 and 81786206.

It is not an unprimeable number, because it can be changed into a prime (81786247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10223277 + ... + 10223284.

Almost surely, 2^81786244 is an apocalyptic number.

It is an amenable number.

81786244 is a deficient number, since it is larger than the sum of its proper divisors (61339690).

81786244 is a wasteful number, since it uses less digits than its factorization.

81786244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20446565 (or 20446563 counting only the distinct ones).

The product of its digits is 86016, while the sum is 40.

The square root of 81786244 is about 9043.5747356894. The cubic root of 81786244 is about 434.0703164257.

The spelling of 81786244 in words is "eighty-one million, seven hundred eighty-six thousand, two hundred forty-four".