66626921 has 2 divisors, whose sum is σ = 66626922. Its totient is φ = 66626920.

The previous prime is 66626873. The next prime is 66626933. The reversal of 66626921 is 12962666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51912025 + 14714896 = 7205^2 + 3836^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66626921 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (66226921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33313460 + 33313461.

It is an arithmetic number, because the mean of its divisors is an integer number (33313461).

Almost surely, 2^66626921 is an apocalyptic number.

It is an amenable number.

66626921 is a deficient number, since it is larger than the sum of its proper divisors (1).

66626921 is an equidigital number, since it uses as much as digits as its factorization.

66626921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46656, while the sum is 38.

The square root of 66626921 is about 8162.5315313327. The cubic root of 66626921 is about 405.3995366283.

The spelling of 66626921 in words is "sixty-six million, six hundred twenty-six thousand, nine hundred twenty-one".