161566516511555 has 4 divisors (see below), whose sum is σ = 193879819813872. Its totient is φ = 129253213209240.

The previous prime is 161566516511527. The next prime is 161566516511567. The reversal of 161566516511555 is 555115615665161.

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

It is not a de Polignac number, because 161566516511555 - 2³² = 161562221544259 is a prime.

It is a super-2 number, since 2×161566516511555² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 161566516511494 and 161566516511503.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16156651651151 + ... + 16156651651160.

It is an arithmetic number, because the mean of its divisors is an integer number (48469954953468).

Almost surely, 2^{161566516511555} is an apocalyptic number.

161566516511555 is a deficient number, since it is larger than the sum of its proper divisors (32313303302317).

161566516511555 is an equidigital number, since it uses as much as digits as its factorization.

161566516511555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32313303302316.

The product of its digits is 20250000, while the sum is 59.

The spelling of 161566516511555 in words is "one hundred sixty-one trillion, five hundred sixty-six billion, five hundred sixteen million, five hundred eleven thousand, five hundred fifty-five".