6845187821 has 2 divisors, whose sum is σ = 6845187822. Its totient is φ = 6845187820.

The previous prime is 6845187809. The next prime is 6845187823. The reversal of 6845187821 is 1287815486.

6845187821 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6558732196 + 286455625 = 80986^2 + 16925^2 .

It is a cyclic number.

It is not a de Polignac number, because 6845187821 - 2¹⁸ = 6844925677 is a prime.

Together with 6845187823, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6845187821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6845187823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3422593910 + 3422593911.

It is an arithmetic number, because the mean of its divisors is an integer number (3422593911).

Almost surely, 2^6845187821 is an apocalyptic number.

It is an amenable number.

6845187821 is a deficient number, since it is larger than the sum of its proper divisors (1).

6845187821 is an equidigital number, since it uses as much as digits as its factorization.

6845187821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 860160, while the sum is 50.

The square root of 6845187821 is about 82735.6502422021. The cubic root of 6845187821 is about 1898.7237801734.

The spelling of 6845187821 in words is "six billion, eight hundred forty-five million, one hundred eighty-seven thousand, eight hundred twenty-one".