161611101565999 has 4 divisors (see below), whose sum is σ = 164660367633336. Its totient is φ = 158561835498664.

The previous prime is 161611101565993. The next prime is 161611101566011. The reversal of 161611101565999 is 999565101116161.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 161611101565999 - 2¹⁹ = 161611101041711 is a prime.

It is a super-2 number, since 2×161611101565999² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (161611101565993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1524633033589 + ... + 1524633033694.

It is an arithmetic number, because the mean of its divisors is an integer number (41165091908334).

Almost surely, 2^{161611101565999} is an apocalyptic number.

161611101565999 is a deficient number, since it is larger than the sum of its proper divisors (3049266067337).

161611101565999 is an equidigital number, since it uses as much as digits as its factorization.

161611101565999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3049266067336.

The product of its (nonzero) digits is 3936600, while the sum is 61.

The spelling of 161611101565999 in words is "one hundred sixty-one trillion, six hundred eleven billion, one hundred one million, five hundred sixty-five thousand, nine hundred ninety-nine".