66857207 has 4 divisors (see below), whose sum is σ = 67990440. Its totient is φ = 65723976.

The previous prime is 66857201. The next prime is 66857227. The reversal of 66857207 is 70275866.

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: 70275866 = 2 ⋅35137933.

It is a cyclic number.

It is not a de Polignac number, because 66857207 - 2⁴ = 66857191 is a prime.

It is a super-2 number, since 2×66857207² = 8939772255681698, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66857201) 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, 566528 + ... + 566645.

It is an arithmetic number, because the mean of its divisors is an integer number (16997610).

Almost surely, 2^66857207 is an apocalyptic number.

66857207 is a deficient number, since it is larger than the sum of its proper divisors (1133233).

66857207 is a wasteful number, since it uses less digits than its factorization.

66857207 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1133232.

The product of its (nonzero) digits is 141120, while the sum is 41.

The square root of 66857207 is about 8176.6256487625. The cubic root of 66857207 is about 405.8660671899.

It can be divided in two parts, 668 and 57207, that added together give a palindrome (57875).

The spelling of 66857207 in words is "sixty-six million, eight hundred fifty-seven thousand, two hundred seven".