78638389 has 4 divisors (see below), whose sum is σ = 78656524. Its totient is φ = 78620256.

The previous prime is 78638387. The next prime is 78638423. The reversal of 78638389 is 98383687.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 98383687 = 563 ⋅174749.

It can be written as a sum of positive squares in 2 ways, for example, as 63075364 + 15563025 = 7942^2 + 3945^2 .

It is a cyclic number.

It is not a de Polignac number, because 78638389 - 2¹ = 78638387 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 (78638381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1699 + ... + 12655.

It is an arithmetic number, because the mean of its divisors is an integer number (19664131).

Almost surely, 2^78638389 is an apocalyptic number.

It is an amenable number.

78638389 is a deficient number, since it is larger than the sum of its proper divisors (18135).

78638389 is a wasteful number, since it uses less digits than its factorization.

78638389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18134.

The product of its digits is 1741824, while the sum is 52.

The square root of 78638389 is about 8867.8288774649. The cubic root of 78638389 is about 428.4283513241.

The spelling of 78638389 in words is "seventy-eight million, six hundred thirty-eight thousand, three hundred eighty-nine".