6691568138 has 4 divisors (see below), whose sum is σ = 10037352210. Its totient is φ = 3345784068.

The previous prime is 6691568137. The next prime is 6691568161. The reversal of 6691568138 is 8318651966.

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

It can be written as a sum of positive squares in only one way, i.e., 5928538009 + 763030129 = 76997^2 + 27623^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 6691568138.

It is not an unprimeable number, because it can be changed into a prime (6691568137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1672892033 + ... + 1672892036.

Almost surely, 2^6691568138 is an apocalyptic number.

6691568138 is a deficient number, since it is larger than the sum of its proper divisors (3345784072).

6691568138 is a wasteful number, since it uses less digits than its factorization.

6691568138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3345784071.

The product of its digits is 1866240, while the sum is 53.

The square root of 6691568138 is about 81802.0057089067. The cubic root of 6691568138 is about 1884.4124643676.

The spelling of 6691568138 in words is "six billion, six hundred ninety-one million, five hundred sixty-eight thousand, one hundred thirty-eight".