66542321 has 2 divisors, whose sum is σ = 66542322. Its totient is φ = 66542320.

The previous prime is 66542279. The next prime is 66542353. The reversal of 66542321 is 12324566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56550400 + 9991921 = 7520^2 + 3161^2 .

It is a cyclic number.

It is not a de Polignac number, because 66542321 - 2¹⁰ = 66541297 is a prime.

It is a super-3 number, since 3×66542321³ (a number of 24 digits) contains 333 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66542621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33271160 + 33271161.

It is an arithmetic number, because the mean of its divisors is an integer number (33271161).

Almost surely, 2^66542321 is an apocalyptic number.

It is an amenable number.

66542321 is a deficient number, since it is larger than the sum of its proper divisors (1).

66542321 is an equidigital number, since it uses as much as digits as its factorization.

66542321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 29.

The square root of 66542321 is about 8157.3476694328. The cubic root of 66542321 is about 405.2278776515.

Adding to 66542321 its reverse (12324566), we get a palindrome (78866887).

The spelling of 66542321 in words is "sixty-six million, five hundred forty-two thousand, three hundred twenty-one".