81837785 has 4 divisors (see below), whose sum is σ = 98205348. Its totient is φ = 65470224.

The previous prime is 81837757. The next prime is 81837793. The reversal of 81837785 is 58773818.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50879689 + 30958096 = 7133^2 + 5564^2 .

It is a cyclic number.

It is not a de Polignac number, because 81837785 - 2²⁰ = 80789209 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8183774 + ... + 8183783.

It is an arithmetic number, because the mean of its divisors is an integer number (24551337).

Almost surely, 2^81837785 is an apocalyptic number.

It is an amenable number.

81837785 is a deficient number, since it is larger than the sum of its proper divisors (16367563).

81837785 is a wasteful number, since it uses less digits than its factorization.

81837785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16367562.

The product of its digits is 376320, while the sum is 47.

The square root of 81837785 is about 9046.4238790806. The cubic root of 81837785 is about 434.1614797603.

The spelling of 81837785 in words is "eighty-one million, eight hundred thirty-seven thousand, seven hundred eighty-five".