161561011517 has 2 divisors, whose sum is σ = 161561011518. Its totient is φ = 161561011516.

The previous prime is 161561011483. The next prime is 161561011519. The reversal of 161561011517 is 715110165161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 157588356676 + 3972654841 = 396974^2 + 63029^2 .

It is a cyclic number.

It is not a de Polignac number, because 161561011517 - 2¹⁰ = 161561010493 is a prime.

It is a super-2 number, since 2×161561011517² (a number of 23 digits) contains 22 as substring.

Together with 161561011519, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161561011519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80780505758 + 80780505759.

It is an arithmetic number, because the mean of its divisors is an integer number (80780505759).

Almost surely, 2^161561011517 is an apocalyptic number.

It is an amenable number.

161561011517 is a deficient number, since it is larger than the sum of its proper divisors (1).

161561011517 is an equidigital number, since it uses as much as digits as its factorization.

161561011517 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6300, while the sum is 35.

Adding to 161561011517 its reverse (715110165161), we get a palindrome (876671176678).

The spelling of 161561011517 in words is "one hundred sixty-one billion, five hundred sixty-one million, eleven thousand, five hundred seventeen".