66678439 has 4 divisors (see below), whose sum is σ = 67158280. Its totient is φ = 66198600.

The previous prime is 66678431. The next prime is 66678473. The reversal of 66678439 is 93487666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66678439 - 2³ = 66678431 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66678392 and 66678401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66678431) 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, 239712 + ... + 239989.

It is an arithmetic number, because the mean of its divisors is an integer number (16789570).

Almost surely, 2^66678439 is an apocalyptic number.

66678439 is a deficient number, since it is larger than the sum of its proper divisors (479841).

66678439 is a wasteful number, since it uses less digits than its factorization.

66678439 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 479840.

The product of its digits is 1306368, while the sum is 49.

The square root of 66678439 is about 8165.6866826985. The cubic root of 66678439 is about 405.5039988699.

The spelling of 66678439 in words is "sixty-six million, six hundred seventy-eight thousand, four hundred thirty-nine".