66990281 has 2 divisors, whose sum is σ = 66990282. Its totient is φ = 66990280.

The previous prime is 66990263. The next prime is 66990289. The reversal of 66990281 is 18209966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62647225 + 4343056 = 7915^2 + 2084^2 .

It is a cyclic number.

It is not a de Polignac number, because 66990281 - 2¹⁰ = 66989257 is a prime.

It is a super-2 number, since 2×66990281² = 8975395496917922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66990289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33495140 + 33495141.

It is an arithmetic number, because the mean of its divisors is an integer number (33495141).

Almost surely, 2^66990281 is an apocalyptic number.

It is an amenable number.

66990281 is a deficient number, since it is larger than the sum of its proper divisors (1).

66990281 is an equidigital number, since it uses as much as digits as its factorization.

66990281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 66990281 is about 8184.7590679262. The cubic root of 66990281 is about 406.1351701964.

The spelling of 66990281 in words is "sixty-six million, nine hundred ninety thousand, two hundred eighty-one".