66815953 has 2 divisors, whose sum is σ = 66815954. Its totient is φ = 66815952.

The previous prime is 66815941. The next prime is 66815977. The reversal of 66815953 is 35951866.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 55606849 + 11209104 = 7457^2 + 3348^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66815953 is a prime.

It is not a weakly prime, because it can be changed into another prime (66815053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33407976 + 33407977.

It is an arithmetic number, because the mean of its divisors is an integer number (33407977).

Almost surely, 2^66815953 is an apocalyptic number.

It is an amenable number.

66815953 is a deficient number, since it is larger than the sum of its proper divisors (1).

66815953 is an equidigital number, since it uses as much as digits as its factorization.

66815953 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 194400, while the sum is 43.

The square root of 66815953 is about 8174.1025807118. The cubic root of 66815953 is about 405.7825706130.

The spelling of 66815953 in words is "sixty-six million, eight hundred fifteen thousand, nine hundred fifty-three".