805684021 has 2 divisors, whose sum is σ = 805684022. Its totient is φ = 805684020.

The previous prime is 805684001. The next prime is 805684039. The reversal of 805684021 is 120486508.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 704902500 + 100781521 = 26550^2 + 10039^2 .

It is a cyclic number.

It is not a de Polignac number, because 805684021 - 2²¹ = 803586869 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (805684001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 402842010 + 402842011.

It is an arithmetic number, because the mean of its divisors is an integer number (402842011).

Almost surely, 2^805684021 is an apocalyptic number.

It is an amenable number.

805684021 is a deficient number, since it is larger than the sum of its proper divisors (1).

805684021 is an equidigital number, since it uses as much as digits as its factorization.

805684021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15360, while the sum is 34.

The square root of 805684021 is about 28384.5736448515. The cubic root of 805684021 is about 930.5111542371.

The spelling of 805684021 in words is "eight hundred five million, six hundred eighty-four thousand, twenty-one".