221644161 has 8 divisors (see below), whose sum is σ = 328361760. Its totient is φ = 147762756.

The previous prime is 221644121. The next prime is 221644201. The reversal of 221644161 is 161446122.

221644161 is a `hidden beast` number, since 2 + 2 + 1 + 644 + 16 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (221644121) and next prime (221644201).

It is not a de Polignac number, because 221644161 - 2⁹ = 221643649 is a prime.

It is a super-2 number, since 2×221644161² = 98252268210787842, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 8209043 = 221644161 / (2 + 2 + 1 + 6 + 4 + 4 + 1 + 6 + 1).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (221644121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4104495 + ... + 4104548.

It is an arithmetic number, because the mean of its divisors is an integer number (41045220).

Almost surely, 2^221644161 is an apocalyptic number.

It is an amenable number.

221644161 is a deficient number, since it is larger than the sum of its proper divisors (106717599).

221644161 is an equidigital number, since it uses as much as digits as its factorization.

221644161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8209052 (or 8209046 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 221644161 is about 14887.7184618732. The cubic root of 221644161 is about 605.1812047431.

The spelling of 221644161 in words is "two hundred twenty-one million, six hundred forty-four thousand, one hundred sixty-one".