66388247 has 4 divisors (see below), whose sum is σ = 70293456. Its totient is φ = 62483040.

The previous prime is 66388243. The next prime is 66388351. The reversal of 66388247 is 74288366.

66388247 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 66388247 - 2² = 66388243 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 66388198 and 66388207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66388243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1952579 + ... + 1952612.

It is an arithmetic number, because the mean of its divisors is an integer number (17573364).

Almost surely, 2^66388247 is an apocalyptic number.

66388247 is a deficient number, since it is larger than the sum of its proper divisors (3905209).

66388247 is a wasteful number, since it uses less digits than its factorization.

66388247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3905208.

The product of its digits is 387072, while the sum is 44.

The square root of 66388247 is about 8147.8983179713. The cubic root of 66388247 is about 404.9148771973.

The spelling of 66388247 in words is "sixty-six million, three hundred eighty-eight thousand, two hundred forty-seven".