6438721903 has 2 divisors, whose sum is σ = 6438721904. Its totient is φ = 6438721902.

The previous prime is 6438721873. The next prime is 6438721931. The reversal of 6438721903 is 3091278346.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6438721903 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6438721903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6438721963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3219360951 + 3219360952.

It is an arithmetic number, because the mean of its divisors is an integer number (3219360952).

Almost surely, 2^6438721903 is an apocalyptic number.

6438721903 is a deficient number, since it is larger than the sum of its proper divisors (1).

6438721903 is an equidigital number, since it uses as much as digits as its factorization.

6438721903 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 217728, while the sum is 43.

The square root of 6438721903 is about 80241.6469359895. The cubic root of 6438721903 is about 1860.3724061624.

The spelling of 6438721903 in words is "six billion, four hundred thirty-eight million, seven hundred twenty-one thousand, nine hundred three".