6918021821 has 2 divisors, whose sum is σ = 6918021822. Its totient is φ = 6918021820.

The previous prime is 6918021797. The next prime is 6918021823. The reversal of 6918021821 is 1281208196.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6134805625 + 783216196 = 78325^2 + 27986^2 .

It is a cyclic number.

It is not a de Polignac number, because 6918021821 - 2³⁰ = 5844279997 is a prime.

Together with 6918021823, 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 (6918021823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3459010910 + 3459010911.

It is an arithmetic number, because the mean of its divisors is an integer number (3459010911).

Almost surely, 2^6918021821 is an apocalyptic number.

It is an amenable number.

6918021821 is a deficient number, since it is larger than the sum of its proper divisors (1).

6918021821 is an equidigital number, since it uses as much as digits as its factorization.

6918021821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 38.

The square root of 6918021821 is about 83174.6465036071. The cubic root of 6918021821 is about 1905.4342872661.

The spelling of 6918021821 in words is "six billion, nine hundred eighteen million, twenty-one thousand, eight hundred twenty-one".