663555161 has 2 divisors, whose sum is σ = 663555162. Its totient is φ = 663555160.

The previous prime is 663555143. The next prime is 663555187. The reversal of 663555161 is 161555366.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644195161 + 19360000 = 25381^2 + 4400^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-663555161 is a prime.

It is not a weakly prime, because it can be changed into another prime (663555461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 331777580 + 331777581.

It is an arithmetic number, because the mean of its divisors is an integer number (331777581).

Almost surely, 2^663555161 is an apocalyptic number.

It is an amenable number.

663555161 is a deficient number, since it is larger than the sum of its proper divisors (1).

663555161 is an equidigital number, since it uses as much as digits as its factorization.

663555161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81000, while the sum is 38.

The square root of 663555161 is about 25759.5644567217. The cubic root of 663555161 is about 872.2192695684.

The spelling of 663555161 in words is "six hundred sixty-three million, five hundred fifty-five thousand, one hundred sixty-one".