6861821 has 2 divisors, whose sum is σ = 6861822. Its totient is φ = 6861820.

The previous prime is 6861817. The next prime is 6861823. The reversal of 6861821 is 1281686.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 4056196 + 2805625 = 2014^2 + 1675^2 .

It is a cyclic number.

It is not a de Polignac number, because 6861821 - 2² = 6861817 is a prime.

Together with 6861823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6861823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3430910 + 3430911.

It is an arithmetic number, because the mean of its divisors is an integer number (3430911).

Almost surely, 2^6861821 is an apocalyptic number.

It is an amenable number.

6861821 is a deficient number, since it is larger than the sum of its proper divisors (1).

6861821 is an equidigital number, since it uses as much as digits as its factorization.

6861821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4608, while the sum is 32.

The square root of 6861821 is about 2619.5077781904. The cubic root of 6861821 is about 190.0260444445.

The spelling of 6861821 in words is "six million, eight hundred sixty-one thousand, eight hundred twenty-one".