978221 has 4 divisors (see below), whose sum is σ = 996732. Its totient is φ = 959712.

The previous prime is 978217. The next prime is 978223. The reversal of 978221 is 122879.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122879 = 103 ⋅1193.

It can be written as a sum of positive squares in 2 ways, for example, as 714025 + 264196 = 845^2 + 514^2 .

It is a cyclic number.

It is not a de Polignac number, because 978221 - 2² = 978217 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (978223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9176 + ... + 9281.

It is an arithmetic number, because the mean of its divisors is an integer number (249183).

2⁹⁷⁸²²¹ is an apocalyptic number.

It is an amenable number.

978221 is a deficient number, since it is larger than the sum of its proper divisors (18511).

978221 is a wasteful number, since it uses less digits than its factorization.

978221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18510.

The product of its digits is 2016, while the sum is 29.

The square root of 978221 is about 989.0505548252. The cubic root of 978221 is about 99.2686983490.

The spelling of 978221 in words is "nine hundred seventy-eight thousand, two hundred twenty-one".