161517606431 has 4 divisors (see below), whose sum is σ = 161518446864. Its totient is φ = 161516766000.

The previous prime is 161517606413. The next prime is 161517606451. The reversal of 161517606431 is 134606715161.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 134606715161 = 47 ⋅2863972663.

It is a cyclic number.

It is not a de Polignac number, because 161517606431 - 2¹⁰ = 161517605407 is a prime.

It is a super-2 number, since 2×161517606431² (a number of 23 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 (161517606451) 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, 26006 + ... + 568956.

It is an arithmetic number, because the mean of its divisors is an integer number (40379611716).

Almost surely, 2^161517606431 is an apocalyptic number.

161517606431 is a deficient number, since it is larger than the sum of its proper divisors (840433).

161517606431 is an equidigital number, since it uses as much as digits as its factorization.

161517606431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 840432.

The product of its (nonzero) digits is 90720, while the sum is 41.

The spelling of 161517606431 in words is "one hundred sixty-one billion, five hundred seventeen million, six hundred six thousand, four hundred thirty-one".