81782785 has 16 divisors (see below), whose sum is σ = 112749696. Its totient is φ = 55784448.

The previous prime is 81782759. The next prime is 81782803. The reversal of 81782785 is 58728718.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81782785 - 2¹⁵ = 81750017 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 702 + ... + 12808.

It is an arithmetic number, because the mean of its divisors is an integer number (7046856).

Almost surely, 2^81782785 is an apocalyptic number.

It is an amenable number.

81782785 is a deficient number, since it is larger than the sum of its proper divisors (30966911).

81782785 is a wasteful number, since it uses less digits than its factorization.

81782785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12312.

The product of its digits is 250880, while the sum is 46.

The square root of 81782785 is about 9043.3834929190. The cubic root of 81782785 is about 434.0641969354.

The spelling of 81782785 in words is "eighty-one million, seven hundred eighty-two thousand, seven hundred eighty-five".