68138815 has 4 divisors (see below), whose sum is σ = 81766584. Its totient is φ = 54511048.

The previous prime is 68138813. The next prime is 68138821. The reversal of 68138815 is 51883186.

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 68138815 - 2¹ = 68138813 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68138813) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6813877 + ... + 6813886.

It is an arithmetic number, because the mean of its divisors is an integer number (20441646).

Almost surely, 2^68138815 is an apocalyptic number.

68138815 is a deficient number, since it is larger than the sum of its proper divisors (13627769).

68138815 is a wasteful number, since it uses less digits than its factorization.

68138815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13627768.

The product of its digits is 46080, while the sum is 40.

The square root of 68138815 is about 8254.6238557550. The cubic root of 68138815 is about 408.4430640355.

The spelling of 68138815 in words is "sixty-eight million, one hundred thirty-eight thousand, eight hundred fifteen".