6438721931 has 2 divisors, whose sum is σ = 6438721932. Its totient is φ = 6438721930.

The previous prime is 6438721903. The next prime is 6438721963. The reversal of 6438721931 is 1391278346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6438721931 - 2¹⁴ = 6438705547 is a prime.

It is a super-2 number, since 2×6438721931² = 82914280209480737522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (6438721031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3219360965 + 3219360966.

It is an arithmetic number, because the mean of its divisors is an integer number (3219360966).

Almost surely, 2^6438721931 is an apocalyptic number.

6438721931 is a deficient number, since it is larger than the sum of its proper divisors (1).

6438721931 is an equidigital number, since it uses as much as digits as its factorization.

6438721931 is an evil number, because the sum of its binary digits is even.

The product of its digits is 217728, while the sum is 44.

The square root of 6438721931 is about 80241.6471104625. The cubic root of 6438721931 is about 1860.3724088591.

The spelling of 6438721931 in words is "six billion, four hundred thirty-eight million, seven hundred twenty-one thousand, nine hundred thirty-one".