6420838981 has 2 divisors, whose sum is σ = 6420838982. Its totient is φ = 6420838980.

The previous prime is 6420838973. The next prime is 6420839053. The reversal of 6420838981 is 1898380246.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6297850881 + 122988100 = 79359^2 + 11090^2 .

It is a cyclic number.

It is not a de Polignac number, because 6420838981 - 2³ = 6420838973 is a prime.

It is a super-2 number, since 2×6420838981² = 82454346439858236722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6420838951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3210419490 + 3210419491.

It is an arithmetic number, because the mean of its divisors is an integer number (3210419491).

Almost surely, 2^6420838981 is an apocalyptic number.

It is an amenable number.

6420838981 is a deficient number, since it is larger than the sum of its proper divisors (1).

6420838981 is an equidigital number, since it uses as much as digits as its factorization.

6420838981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 663552, while the sum is 49.

The square root of 6420838981 is about 80130.1377822352. The cubic root of 6420838981 is about 1858.6484748649.

The spelling of 6420838981 in words is "six billion, four hundred twenty million, eight hundred thirty-eight thousand, nine hundred eighty-one".