78115813 has 4 divisors (see below), whose sum is σ = 78451308. Its totient is φ = 77780320.

The previous prime is 78115811. The next prime is 78115837. The reversal of 78115813 is 31851187.

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

It can be written as a sum of positive squares in 2 ways, for example, as 32512804 + 45603009 = 5702^2 + 6753^2 .

It is a cyclic number.

It is not a de Polignac number, because 78115813 - 2¹ = 78115811 is a prime.

It is a super-2 number, since 2×78115813² = 12204160481301938, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78115811) 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, 167398 + ... + 167863.

It is an arithmetic number, because the mean of its divisors is an integer number (19612827).

Almost surely, 2^78115813 is an apocalyptic number.

It is an amenable number.

78115813 is a deficient number, since it is larger than the sum of its proper divisors (335495).

78115813 is a wasteful number, since it uses less digits than its factorization.

78115813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 335494.

The product of its digits is 6720, while the sum is 34.

The square root of 78115813 is about 8838.3150543528. The cubic root of 78115813 is about 427.4772291600.

The spelling of 78115813 in words is "seventy-eight million, one hundred fifteen thousand, eight hundred thirteen".