161603557 has 2 divisors, whose sum is σ = 161603558. Its totient is φ = 161603556.

The previous prime is 161603521. The next prime is 161603567. The reversal of 161603557 is 755306161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134884996 + 26718561 = 11614^2 + 5169^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161603557 is a prime.

It is a super-2 number, since 2×161603557² = 52231419270104498, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161603567) 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, 80801778 + 80801779.

It is an arithmetic number, because the mean of its divisors is an integer number (80801779).

Almost surely, 2^161603557 is an apocalyptic number.

It is an amenable number.

161603557 is a deficient number, since it is larger than the sum of its proper divisors (1).

161603557 is an equidigital number, since it uses as much as digits as its factorization.

161603557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18900, while the sum is 34.

The square root of 161603557 is about 12712.3387698724. The cubic root of 161603557 is about 544.6911326791.

The spelling of 161603557 in words is "one hundred sixty-one million, six hundred three thousand, five hundred fifty-seven".