81770 has 32 divisors (see below), whose sum is σ = 172368. Its totient is φ = 27648.

The previous prime is 81769. The next prime is 81773. The reversal of 81770 is 7718.

It can be written as a sum of positive squares in 8 ways, for example, as 49729 + 32041 = 223^2 + 179^2 .

It is not an unprimeable number, because it can be changed into a prime (81773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2192 + ... + 2228.

2⁸¹⁷⁷⁰ is an apocalyptic number.

81770 is an abundant number, since it is smaller than the sum of its proper divisors (90598).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86184).

81770 is a wasteful number, since it uses less digits than its factorization.

81770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74.

The product of its (nonzero) digits is 392, while the sum is 23.

The square root of 81770 is about 285.9545418419. The cubic root of 81770 is about 43.4041576853.

The spelling of 81770 in words is "eighty-one thousand, seven hundred seventy".