66239815 has 8 divisors (see below), whose sum is σ = 80260128. Its totient is φ = 52476960.

The previous prime is 66239801. The next prime is 66239819. The reversal of 66239815 is 51893266.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66239815 - 2⁵ = 66239783 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 (66239819) 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 7 ways as a sum of consecutive naturals, for example, 63796 + ... + 64825.

It is an arithmetic number, because the mean of its divisors is an integer number (10032516).

Almost surely, 2^66239815 is an apocalyptic number.

66239815 is a deficient number, since it is larger than the sum of its proper divisors (14020313).

66239815 is a wasteful number, since it uses less digits than its factorization.

66239815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128729.

The product of its digits is 77760, while the sum is 40.

The square root of 66239815 is about 8138.7846144249. The cubic root of 66239815 is about 404.6128801014.

The spelling of 66239815 in words is "sixty-six million, two hundred thirty-nine thousand, eight hundred fifteen".