81770085 has 48 divisors (see below), whose sum is σ = 151884720. Its totient is φ = 40550400.

The previous prime is 81770081. The next prime is 81770107. The reversal of 81770085 is 58007718.

It can be written as a sum of positive squares in 8 ways, for example, as 16208676 + 65561409 = 4026^2 + 8097^2 .

It is not a de Polignac number, because 81770085 - 2² = 81770081 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81770081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67485 + ... + 68685.

It is an arithmetic number, because the mean of its divisors is an integer number (3164265).

Almost surely, 2^81770085 is an apocalyptic number.

81770085 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81770085 is a deficient number, since it is larger than the sum of its proper divisors (70114635).

81770085 is a wasteful number, since it uses less digits than its factorization.

81770085 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1318 (or 1315 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 36.

The square root of 81770085 is about 9042.6812948373. The cubic root of 81770085 is about 434.0417272486.

The spelling of 81770085 in words is "eighty-one million, seven hundred seventy thousand, eighty-five".