78638257 has 4 divisors (see below), whose sum is σ = 78761200. Its totient is φ = 78515316.

The previous prime is 78638249. The next prime is 78638279. The reversal of 78638257 is 75283687.

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: 75283687 = 7459 ⋅10093.

It is a cyclic number.

It is not a de Polignac number, because 78638257 - 2³ = 78638249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78638057) 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, 60507 + ... + 61792.

It is an arithmetic number, because the mean of its divisors is an integer number (19690300).

Almost surely, 2^78638257 is an apocalyptic number.

It is an amenable number.

78638257 is a deficient number, since it is larger than the sum of its proper divisors (122943).

78638257 is a wasteful number, since it uses less digits than its factorization.

78638257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122942.

The product of its digits is 564480, while the sum is 46.

The square root of 78638257 is about 8867.8214348283. The cubic root of 78638257 is about 428.4281116084.

The spelling of 78638257 in words is "seventy-eight million, six hundred thirty-eight thousand, two hundred fifty-seven".