97781 has 4 divisors (see below), whose sum is σ = 98412. Its totient is φ = 97152.
The previous prime is 97777. The next prime is 97787. The reversal of 97781 is 18779.
97781 is nontrivially palindromic in base 4.
It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18779 = 89 ⋅211.
It can be written as a sum of positive squares in 2 ways, for example, as 27556 + 70225 = 166^2 + 265^2 .
It is a cyclic number.
It is not a de Polignac number, because 97781 - 22 = 97777 is a prime.
It is a super-2 number, since 2×977812 = 19122247922, which contains 22 as substring.
It is a Duffinian number.
It is a plaindrome in base 13.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (97787) 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 3 ways as a sum of consecutive naturals, for example, 101 + ... + 453.
It is an arithmetic number, because the mean of its divisors is an integer number (24603).
297781 is an apocalyptic number.
It is an amenable number.
97781 is a deficient number, since it is larger than the sum of its proper divisors (631).
97781 is a wasteful number, since it uses less digits than its factorization.
97781 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 630.
The product of its digits is 3528, while the sum is 32.
The square root of 97781 is about 312.6995362964. The cubic root of 97781 is about 46.0699942609.
It can be divided in two parts, 9778 and 1, that added together give a palindrome (9779).
The spelling of 97781 in words is "ninety-seven thousand, seven hundred eighty-one".
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