81319785 has 16 divisors (see below), whose sum is σ = 130505856. Its totient is φ = 43239168.

The previous prime is 81319757. The next prime is 81319793. The reversal of 81319785 is 58791318.

It is not a de Polignac number, because 81319785 - 2¹¹ = 81317737 is a prime.

It is a super-2 number, since 2×81319785² = 13225814864892450, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2989 + ... + 13098.

It is an arithmetic number, because the mean of its divisors is an integer number (8156616).

Almost surely, 2^81319785 is an apocalyptic number.

It is an amenable number.

81319785 is a deficient number, since it is larger than the sum of its proper divisors (49186071).

81319785 is a wasteful number, since it uses less digits than its factorization.

81319785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16432.

The product of its digits is 60480, while the sum is 42.

The square root of 81319785 is about 9017.7483331484. The cubic root of 81319785 is about 433.2435182036.

The spelling of 81319785 in words is "eighty-one million, three hundred nineteen thousand, seven hundred eighty-five".