161566214209 has 3 divisors (see below), whose sum is σ = 161566616163. Its totient is φ = 161565812256.

The previous prime is 161566214179. The next prime is 161566214213. The reversal of 161566214209 is 902412665161.

The square root of 161566214209 is 401953.

It is a perfect power (a square), and thus also a powerful number.

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.

It can be written as a sum of positive squares in only one way, i.e., 149625844225 + 11940369984 = 386815^2 + 109272^2 .

It is not a de Polignac number, because 161566214209 - 2⁵ = 161566214177 is a prime.

It is a super-2 number, since 2×161566214209² (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 (161566214809) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 200977 + ... + 602929.

It is an arithmetic number, because the mean of its divisors is an integer number (53855538721).

Almost surely, 2^161566214209 is an apocalyptic number.

161566214209 is the 401953-rd square number.

161566214209 is the 200977-th centered octagonal number.

It is an amenable number.

161566214209 is a deficient number, since it is larger than the sum of its proper divisors (401954).

161566214209 is an frugal number, since it uses more digits than its factorization.

161566214209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 803906 (or 401953 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 43.

The spelling of 161566214209 in words is "one hundred sixty-one billion, five hundred sixty-six million, two hundred fourteen thousand, two hundred nine".