221428161 has 12 divisors (see below), whose sum is σ = 331686992. Its totient is φ = 147618612.

The previous prime is 221428127. The next prime is 221428187. The reversal of 221428161 is 161824122.

221428161 is a `hidden beast` number, since 221 + 428 + 16 + 1 = 666.

221428161 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 221428161 - 2¹³ = 221419969 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221420161) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 455371 + ... + 455856.

Almost surely, 2^221428161 is an apocalyptic number.

It is an amenable number.

221428161 is a deficient number, since it is larger than the sum of its proper divisors (110258831).

221428161 is an frugal number, since it uses more digits than its factorization.

221428161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 911242 (or 911230 counting only the distinct ones).

The product of its digits is 1536, while the sum is 27.

The square root of 221428161 is about 14880.4623920092. The cubic root of 221428161 is about 604.9845507518.

It can be divided in two parts, 22142 and 8161, that added together give a palindrome (30303).

The spelling of 221428161 in words is "two hundred twenty-one million, four hundred twenty-eight thousand, one hundred sixty-one".