66351281 has 2 divisors, whose sum is σ = 66351282. Its totient is φ = 66351280.

The previous prime is 66351247. The next prime is 66351293. The reversal of 66351281 is 18215366.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66178225 + 173056 = 8135^2 + 416^2 .

It is a cyclic number.

It is not a de Polignac number, because 66351281 - 2¹⁸ = 66089137 is a prime.

It is a super-3 number, since 3×66351281³ (a number of 24 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66353281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33175640 + 33175641.

It is an arithmetic number, because the mean of its divisors is an integer number (33175641).

Almost surely, 2^66351281 is an apocalyptic number.

It is an amenable number.

66351281 is a deficient number, since it is larger than the sum of its proper divisors (1).

66351281 is an equidigital number, since it uses as much as digits as its factorization.

66351281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8640, while the sum is 32.

The square root of 66351281 is about 8145.6295643738. The cubic root of 66351281 is about 404.8397089607.

The spelling of 66351281 in words is "sixty-six million, three hundred fifty-one thousand, two hundred eighty-one".