161561663 has 2 divisors, whose sum is σ = 161561664. Its totient is φ = 161561662.

The previous prime is 161561623. The next prime is 161561711. The reversal of 161561663 is 366165161.

It is a weak prime.

It is an emirp because it is prime and its reverse (366165161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161561663 - 2¹² = 161557567 is a prime.

It is a super-2 number, since 2×161561663² = 52204341902651138, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161561623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80780831 + 80780832.

It is an arithmetic number, because the mean of its divisors is an integer number (80780832).

Almost surely, 2^161561663 is an apocalyptic number.

161561663 is a deficient number, since it is larger than the sum of its proper divisors (1).

161561663 is an equidigital number, since it uses as much as digits as its factorization.

161561663 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 35.

The square root of 161561663 is about 12710.6908938893. The cubic root of 161561663 is about 544.6440601540.

The spelling of 161561663 in words is "one hundred sixty-one million, five hundred sixty-one thousand, six hundred sixty-three".