863685661 has 2 divisors, whose sum is σ = 863685662. Its totient is φ = 863685660.

The previous prime is 863685577. The next prime is 863685701. The reversal of 863685661 is 166586368.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 672416761 + 191268900 = 25931^2 + 13830^2 .

It is a cyclic number.

It is not a de Polignac number, because 863685661 - 2⁹ = 863685149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (863685161) 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 as a sum of consecutive naturals, namely, 431842830 + 431842831.

It is an arithmetic number, because the mean of its divisors is an integer number (431842831).

Almost surely, 2^863685661 is an apocalyptic number.

It is an amenable number.

863685661 is a deficient number, since it is larger than the sum of its proper divisors (1).

863685661 is an equidigital number, since it uses as much as digits as its factorization.

863685661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1244160, while the sum is 49.

The square root of 863685661 is about 29388.5294120002. The cubic root of 863685661 is about 952.3251120642.

It can be divided in two parts, 86368 and 5661, that added together give a palindrome (92029).

The spelling of 863685661 in words is "eight hundred sixty-three million, six hundred eighty-five thousand, six hundred sixty-one".