78727217 has 4 divisors (see below), whose sum is σ = 79162356. Its totient is φ = 78292080.

The previous prime is 78727189. The next prime is 78727219. The reversal of 78727217 is 71272787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71272787 = 97 ⋅734771.

It can be written as a sum of positive squares in 2 ways, for example, as 40398736 + 38328481 = 6356^2 + 6191^2 .

It is a cyclic number.

It is not a de Polignac number, because 78727217 - 2⁸ = 78726961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78727219) 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, 217298 + ... + 217659.

It is an arithmetic number, because the mean of its divisors is an integer number (19790589).

Almost surely, 2^78727217 is an apocalyptic number.

It is an amenable number.

78727217 is a deficient number, since it is larger than the sum of its proper divisors (435139).

78727217 is a wasteful number, since it uses less digits than its factorization.

78727217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435138.

The product of its digits is 76832, while the sum is 41.

The square root of 78727217 is about 8872.8359051658. The cubic root of 78727217 is about 428.5896046841.

The spelling of 78727217 in words is "seventy-eight million, seven hundred twenty-seven thousand, two hundred seventeen".