66551593 has 2 divisors, whose sum is σ = 66551594. Its totient is φ = 66551592.

The previous prime is 66551591. The next prime is 66551647. The reversal of 66551593 is 39515566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 42029289 + 24522304 = 6483^2 + 4952^2 .

It is a cyclic number.

It is not a de Polignac number, because 66551593 - 2¹ = 66551591 is a prime.

It is a super-2 number, since 2×66551593² = 8858229061675298, which contains 22 as substring.

Together with 66551591, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66551591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33275796 + 33275797.

It is an arithmetic number, because the mean of its divisors is an integer number (33275797).

Almost surely, 2^66551593 is an apocalyptic number.

It is an amenable number.

66551593 is a deficient number, since it is larger than the sum of its proper divisors (1).

66551593 is an equidigital number, since it uses as much as digits as its factorization.

66551593 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 121500, while the sum is 40.

The square root of 66551593 is about 8157.9159716192. The cubic root of 66551593 is about 405.2466982473.

The spelling of 66551593 in words is "sixty-six million, five hundred fifty-one thousand, five hundred ninety-three".