78921317 has 4 divisors (see below), whose sum is σ = 79269216. Its totient is φ = 78573420.

The previous prime is 78921301. The next prime is 78921329. The reversal of 78921317 is 71312987.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 71312987 = 647 ⋅110221.

It is a cyclic number.

It is not a de Polignac number, because 78921317 - 2⁴ = 78921301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78921397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 173609 + ... + 174062.

It is an arithmetic number, because the mean of its divisors is an integer number (19817304).

Almost surely, 2^78921317 is an apocalyptic number.

It is an amenable number.

78921317 is a deficient number, since it is larger than the sum of its proper divisors (347899).

78921317 is a wasteful number, since it uses less digits than its factorization.

78921317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347898.

The product of its digits is 21168, while the sum is 38.

The square root of 78921317 is about 8883.7670500751. The cubic root of 78921317 is about 428.9415412906.

The spelling of 78921317 in words is "seventy-eight million, nine hundred twenty-one thousand, three hundred seventeen".