66595981 has 2 divisors, whose sum is σ = 66595982. Its totient is φ = 66595980.

The previous prime is 66595961. The next prime is 66595993. The reversal of 66595981 is 18959566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52794756 + 13801225 = 7266^2 + 3715^2 .

It is a cyclic number.

It is not a de Polignac number, because 66595981 - 2⁷ = 66595853 is a prime.

It is a super-2 number, since 2×66595981² = 8870049370704722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66595951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33297990 + 33297991.

It is an arithmetic number, because the mean of its divisors is an integer number (33297991).

Almost surely, 2^66595981 is an apocalyptic number.

It is an amenable number.

66595981 is a deficient number, since it is larger than the sum of its proper divisors (1).

66595981 is an equidigital number, since it uses as much as digits as its factorization.

66595981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 583200, while the sum is 49.

The square root of 66595981 is about 8160.6360658958. The cubic root of 66595981 is about 405.3367741916.

It can be divided in two parts, 66595 and 981, that added together give a palindrome (67576).

The spelling of 66595981 in words is "sixty-six million, five hundred ninety-five thousand, nine hundred eighty-one".