66518839 has 4 divisors (see below), whose sum is σ = 68664640. Its totient is φ = 64373040.

The previous prime is 66518831. The next prime is 66518849. The reversal of 66518839 is 93881566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 93881566 = 2 ⋅46940783.

It is a cyclic number.

It is not a de Polignac number, because 66518839 - 2³ = 66518831 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 (66518831) 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, 1072854 + ... + 1072915.

It is an arithmetic number, because the mean of its divisors is an integer number (17166160).

Almost surely, 2^66518839 is an apocalyptic number.

66518839 is a deficient number, since it is larger than the sum of its proper divisors (2145801).

66518839 is a wasteful number, since it uses less digits than its factorization.

66518839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2145800.

The product of its digits is 311040, while the sum is 46.

The square root of 66518839 is about 8155.9082265558. The cubic root of 66518839 is about 405.1802053311.

The spelling of 66518839 in words is "sixty-six million, five hundred eighteen thousand, eight hundred thirty-nine".