78438686 has 4 divisors (see below), whose sum is σ = 117658032. Its totient is φ = 39219342.

The previous prime is 78438677. The next prime is 78438691. The reversal of 78438686 is 68683487.

It is a happy number.

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

It is a super-2 number, since 2×78438686² = 12305254922813192, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19609670 + ... + 19609673.

It is an arithmetic number, because the mean of its divisors is an integer number (29414508).

Almost surely, 2^78438686 is an apocalyptic number.

78438686 is a deficient number, since it is larger than the sum of its proper divisors (39219346).

78438686 is a wasteful number, since it uses less digits than its factorization.

78438686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39219345.

The product of its digits is 1548288, while the sum is 50.

The square root of 78438686 is about 8856.5617482181. The cubic root of 78438686 is about 428.0653778197.

The spelling of 78438686 in words is "seventy-eight million, four hundred thirty-eight thousand, six hundred eighty-six".