66857231 has 4 divisors (see below), whose sum is σ = 76408272. Its totient is φ = 57306192.

The previous prime is 66857227. The next prime is 66857279. The reversal of 66857231 is 13275866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13275866 = 2 ⋅6637933.

It is a cyclic number.

It is not a de Polignac number, because 66857231 - 2² = 66857227 is a prime.

It is a super-2 number, since 2×66857231² = 8939778673974722, 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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4775510 + ... + 4775523.

It is an arithmetic number, because the mean of its divisors is an integer number (19102068).

Almost surely, 2^66857231 is an apocalyptic number.

66857231 is a deficient number, since it is larger than the sum of its proper divisors (9551041).

66857231 is an equidigital number, since it uses as much as digits as its factorization.

66857231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9551040.

The product of its digits is 60480, while the sum is 38.

The square root of 66857231 is about 8176.6271163604. The cubic root of 66857231 is about 405.8661157550.

The spelling of 66857231 in words is "sixty-six million, eight hundred fifty-seven thousand, two hundred thirty-one".