161615517601 has 4 divisors (see below), whose sum is σ = 171122312772. Its totient is φ = 152108722432.

The previous prime is 161615517589. The next prime is 161615517641. The reversal of 161615517601 is 106715516161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 106715516161 = 12281 ⋅8689481.

It can be written as a sum of positive squares in 2 ways, for example, as 116416757601 + 45198760000 = 341199^2 + 212600^2 .

It is a cyclic number.

It is not a de Polignac number, because 161615517601 - 2³¹ = 159468033953 is a prime.

It is a super-2 number, since 2×161615517601² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161615517641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4753397560 + ... + 4753397593.

It is an arithmetic number, because the mean of its divisors is an integer number (42780578193).

Almost surely, 2^161615517601 is an apocalyptic number.

It is an amenable number.

161615517601 is a deficient number, since it is larger than the sum of its proper divisors (9506795171).

161615517601 is an equidigital number, since it uses as much as digits as its factorization.

161615517601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9506795170.

The product of its (nonzero) digits is 37800, while the sum is 40.

The spelling of 161615517601 in words is "one hundred sixty-one billion, six hundred fifteen million, five hundred seventeen thousand, six hundred one".