6991128238 has 4 divisors (see below), whose sum is σ = 10486692360. Its totient is φ = 3495564118.

The previous prime is 6991128233. The next prime is 6991128251. The reversal of 6991128238 is 8328211996.

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

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 6991128191 and 6991128200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6991128233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1747782058 + ... + 1747782061.

It is an arithmetic number, because the mean of its divisors is an integer number (2621673090).

Almost surely, 2^6991128238 is an apocalyptic number.

6991128238 is a deficient number, since it is larger than the sum of its proper divisors (3495564122).

6991128238 is a wasteful number, since it uses less digits than its factorization.

6991128238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3495564121.

The product of its digits is 373248, while the sum is 49.

The square root of 6991128238 is about 83612.9669249932. The cubic root of 6991128238 is about 1912.1226949196.

The spelling of 6991128238 in words is "six billion, nine hundred ninety-one million, one hundred twenty-eight thousand, two hundred thirty-eight".