978821 has 2 divisors, whose sum is σ = 978822. Its totient is φ = 978820.

The previous prime is 978799. The next prime is 978839. The reversal of 978821 is 128879.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 504100 + 474721 = 710^2 + 689^2 .

It is an emirp because it is prime and its reverse (128879) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-978821 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (978851) 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 as a sum of consecutive naturals, namely, 489410 + 489411.

It is an arithmetic number, because the mean of its divisors is an integer number (489411).

2⁹⁷⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

978821 is a deficient number, since it is larger than the sum of its proper divisors (1).

978821 is an equidigital number, since it uses as much as digits as its factorization.

978821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8064, while the sum is 35.

The square root of 978821 is about 989.3538295271. The cubic root of 978821 is about 99.2889899619.

The spelling of 978821 in words is "nine hundred seventy-eight thousand, eight hundred twenty-one".