78517321 has 3 divisors (see below), whose sum is σ = 78526183. Its totient is φ = 78508460.

The previous prime is 78517289. The next prime is 78517333. The reversal of 78517321 is 12371587.

The square root of 78517321 is 8861.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 12371587 = 281 ⋅44027.

It can be written as a sum of positive squares in only one way, i.e., 77633721 + 883600 = 8811^2 + 940^2 .

It is not a de Polignac number, because 78517321 - 2⁵ = 78517289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78517381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 4431 + ... + 13291.

Almost surely, 2^78517321 is an apocalyptic number.

78517321 is the 8861-st square number.

78517321 is the 4431-st centered octagonal number.

It is an amenable number.

78517321 is a deficient number, since it is larger than the sum of its proper divisors (8862).

78517321 is an frugal number, since it uses more digits than its factorization.

78517321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17722 (or 8861 counting only the distinct ones).

The product of its digits is 11760, while the sum is 34.

The cubic root of 78517321 is about 428.2083756208.

The spelling of 78517321 in words is "seventy-eight million, five hundred seventeen thousand, three hundred twenty-one".