66646913 has 2 divisors, whose sum is σ = 66646914. Its totient is φ = 66646912.

The previous prime is 66646907. The next prime is 66646949. The reversal of 66646913 is 31964666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61575409 + 5071504 = 7847^2 + 2252^2 .

It is a cyclic number.

It is not a de Polignac number, because 66646913 - 2⁴ = 66646897 is a prime.

It is a super-2 number, since 2×66646913² = 8883622024859138, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (66646903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33323456 + 33323457.

It is an arithmetic number, because the mean of its divisors is an integer number (33323457).

Almost surely, 2^66646913 is an apocalyptic number.

It is an amenable number.

66646913 is a deficient number, since it is larger than the sum of its proper divisors (1).

66646913 is an equidigital number, since it uses as much as digits as its factorization.

66646913 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 41.

The square root of 66646913 is about 8163.7560595598. The cubic root of 66646913 is about 405.4400804851.

The spelling of 66646913 in words is "sixty-six million, six hundred forty-six thousand, nine hundred thirteen".