221800161 has 16 divisors (see below), whose sum is σ = 325087488. Its totient is φ = 133395600.

The previous prime is 221800157. The next prime is 221800199. The reversal of 221800161 is 161008122.

221800161 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 221800161 - 2² = 221800157 is a prime.

It is a super-2 number, since 2×221800161² = 98390622839251842, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221800861) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21331 + ... + 29976.

It is an arithmetic number, because the mean of its divisors is an integer number (20317968).

Almost surely, 2^221800161 is an apocalyptic number.

It is an amenable number.

221800161 is a deficient number, since it is larger than the sum of its proper divisors (103287327).

221800161 is a wasteful number, since it uses less digits than its factorization.

221800161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51452.

The product of its (nonzero) digits is 192, while the sum is 21.

The square root of 221800161 is about 14892.9567581458. The cubic root of 221800161 is about 605.3231531812.

Adding to 221800161 its reverse (161008122), we get a palindrome (382808283).

The spelling of 221800161 in words is "two hundred twenty-one million, eight hundred thousand, one hundred sixty-one".