78257217 has 4 divisors (see below), whose sum is σ = 104342960. Its totient is φ = 52171476.

The previous prime is 78257213. The next prime is 78257261. The reversal of 78257217 is 71275287.

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: 71275287 = 3 ⋅23758429.

It is not a de Polignac number, because 78257217 - 2² = 78257213 is a prime.

It is a super-2 number, since 2×78257217² = 12248384025170178, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78257213) 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, 13042867 + ... + 13042872.

It is an arithmetic number, because the mean of its divisors is an integer number (26085740).

Almost surely, 2^78257217 is an apocalyptic number.

It is an amenable number.

78257217 is a deficient number, since it is larger than the sum of its proper divisors (26085743).

78257217 is a wasteful number, since it uses less digits than its factorization.

78257217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26085742.

The product of its digits is 54880, while the sum is 39.

The square root of 78257217 is about 8846.3109260301. The cubic root of 78257217 is about 427.7350111678.

The spelling of 78257217 in words is "seventy-eight million, two hundred fifty-seven thousand, two hundred seventeen".