66723257 has 2 divisors, whose sum is σ = 66723258. Its totient is φ = 66723256.

The previous prime is 66723233. The next prime is 66723259. The reversal of 66723257 is 75232766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66650896 + 72361 = 8164^2 + 269^2 .

It is a cyclic number.

It is not a de Polignac number, because 66723257 - 2¹⁸ = 66461113 is a prime.

Together with 66723259, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66723257.

It is not a weakly prime, because it can be changed into another prime (66723259) 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 as a sum of consecutive naturals, namely, 33361628 + 33361629.

It is an arithmetic number, because the mean of its divisors is an integer number (33361629).

Almost surely, 2^66723257 is an apocalyptic number.

It is an amenable number.

66723257 is a deficient number, since it is larger than the sum of its proper divisors (1).

66723257 is an equidigital number, since it uses as much as digits as its factorization.

66723257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 105840, while the sum is 38.

The square root of 66723257 is about 8168.4305102021. The cubic root of 66723257 is about 405.5948318696.

The spelling of 66723257 in words is "sixty-six million, seven hundred twenty-three thousand, two hundred fifty-seven".