78721715 has 4 divisors (see below), whose sum is σ = 94466064. Its totient is φ = 62977368.

The previous prime is 78721697. The next prime is 78721739. The reversal of 78721715 is 51712787.

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 78721715 - 2⁶ = 78721651 is a prime.

It is a Duffinian number.

It is a plaindrome in base 12.

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 in 3 ways as a sum of consecutive naturals, for example, 7872167 + ... + 7872176.

It is an arithmetic number, because the mean of its divisors is an integer number (23616516).

Almost surely, 2^78721715 is an apocalyptic number.

78721715 is a deficient number, since it is larger than the sum of its proper divisors (15744349).

78721715 is a wasteful number, since it uses less digits than its factorization.

78721715 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15744348.

The product of its digits is 27440, while the sum is 38.

The square root of 78721715 is about 8872.5258523151. The cubic root of 78721715 is about 428.5796201873.

The spelling of 78721715 in words is "seventy-eight million, seven hundred twenty-one thousand, seven hundred fifteen".