878021 has 2 divisors, whose sum is σ = 878022. Its totient is φ = 878020.

The previous prime is 878011. The next prime is 878023. The reversal of 878021 is 120878.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 784996 + 93025 = 886^2 + 305^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-878021 is a prime.

Together with 878023, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (878023) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 439010 + 439011.

It is an arithmetic number, because the mean of its divisors is an integer number (439011).

2⁸⁷⁸⁰²¹ is an apocalyptic number.

It is an amenable number.

878021 is a deficient number, since it is larger than the sum of its proper divisors (1).

878021 is an equidigital number, since it uses as much as digits as its factorization.

878021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 896, while the sum is 26.

The square root of 878021 is about 937.0277477215. The cubic root of 878021 is about 95.7565082256.

Adding to 878021 its reverse (120878), we get a palindrome (998899).

The spelling of 878021 in words is "eight hundred seventy-eight thousand, twenty-one".