81787 has 6 divisors (see below), whose sum is σ = 87188. Its totient is φ = 76704.

The previous prime is 81773. The next prime is 81799. The reversal of 81787 is 78718.

It is not a de Polignac number, because 81787 - 2¹⁵ = 49019 is a prime.

It is a super-2 number, since 2×81787² = 13378226738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81707) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 148 + ... + 430.

2⁸¹⁷⁸⁷ is an apocalyptic number.

81787 is a deficient number, since it is larger than the sum of its proper divisors (5401).

81787 is a wasteful number, since it uses less digits than its factorization.

81787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 300 counting only the distinct ones).

The product of its digits is 3136, while the sum is 31.

The square root of 81787 is about 285.9842653014. The cubic root of 81787 is about 43.4071653880.

Adding to 81787 its sum of digits (31), we get a palindrome (81818).

It can be divided in two parts, 81 and 787, that added together give a palindrome (868).

The spelling of 81787 in words is "eighty-one thousand, seven hundred eighty-seven".