878212021 has 2 divisors, whose sum is σ = 878212022. Its totient is φ = 878212020.

The previous prime is 878212009. The next prime is 878212031. The reversal of 878212021 is 120212878.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 828000625 + 50211396 = 28775^2 + 7086^2 .

It is a cyclic number.

It is not a de Polignac number, because 878212021 - 2¹⁷ = 878080949 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (878212001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 439106010 + 439106011.

It is an arithmetic number, because the mean of its divisors is an integer number (439106011).

Almost surely, 2^878212021 is an apocalyptic number.

It is an amenable number.

878212021 is a deficient number, since it is larger than the sum of its proper divisors (1).

878212021 is an equidigital number, since it uses as much as digits as its factorization.

878212021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3584, while the sum is 31.

The square root of 878212021 is about 29634.6422451833. The cubic root of 878212021 is about 957.6345193867.

Adding to 878212021 its reverse (120212878), we get a palindrome (998424899).

The spelling of 878212021 in words is "eight hundred seventy-eight million, two hundred twelve thousand, twenty-one".