161201391817 has 2 divisors, whose sum is σ = 161201391818. Its totient is φ = 161201391816.

The previous prime is 161201391803. The next prime is 161201391823. The reversal of 161201391817 is 718193102161.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 156300831801 + 4900560016 = 395349^2 + 70004^2 .

It is an emirp because it is prime and its reverse (718193102161) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 161201391817 - 2¹⁵ = 161201359049 is a prime.

It is a super-2 number, since 2×161201391817² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 161201391817.

It is not a weakly prime, because it can be changed into another prime (161201391317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80600695908 + 80600695909.

It is an arithmetic number, because the mean of its divisors is an integer number (80600695909).

Almost surely, 2^161201391817 is an apocalyptic number.

It is an amenable number.

161201391817 is a deficient number, since it is larger than the sum of its proper divisors (1).

161201391817 is an equidigital number, since it uses as much as digits as its factorization.

161201391817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 40.

Adding to 161201391817 its reverse (718193102161), we get a palindrome (879394493978).

The spelling of 161201391817 in words is "one hundred sixty-one billion, two hundred one million, three hundred ninety-one thousand, eight hundred seventeen".