6378991939 has 4 divisors (see below), whose sum is σ = 6393724456. Its totient is φ = 6364259424.

The previous prime is 6378991937. The next prime is 6378991943. The reversal of 6378991939 is 9391998736.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6378991939 - 2¹ = 6378991937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6378991937) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7365609 + ... + 7366474.

It is an arithmetic number, because the mean of its divisors is an integer number (1598431114).

Almost surely, 2^6378991939 is an apocalyptic number.

6378991939 is a deficient number, since it is larger than the sum of its proper divisors (14732517).

6378991939 is a wasteful number, since it uses less digits than its factorization.

6378991939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14732516.

The product of its digits is 19840464, while the sum is 64.

The square root of 6378991939 is about 79868.5916928551. The cubic root of 6378991939 is about 1854.6018319929.

The spelling of 6378991939 in words is "six billion, three hundred seventy-eight million, nine hundred ninety-one thousand, nine hundred thirty-nine".