9781861 has 2 divisors, whose sum is σ = 9781862. Its totient is φ = 9781860.

The previous prime is 9781853. The next prime is 9781867. The reversal of 9781861 is 1681879.

9781861 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5904900 + 3876961 = 2430^2 + 1969^2 .

It is an emirp because it is prime and its reverse (1681879) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9781861 - 2³ = 9781853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9781867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890930 + 4890931.

It is an arithmetic number, because the mean of its divisors is an integer number (4890931).

Almost surely, 2^9781861 is an apocalyptic number.

It is an amenable number.

9781861 is a deficient number, since it is larger than the sum of its proper divisors (1).

9781861 is an equidigital number, since it uses as much as digits as its factorization.

9781861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24192, while the sum is 40.

The square root of 9781861 is about 3127.5966811595. The cubic root of 9781861 is about 213.8653839378.

It can be divided in two parts, 97818 and 61, that added together give a palindrome (97879).

The spelling of 9781861 in words is "nine million, seven hundred eighty-one thousand, eight hundred sixty-one".