66943621 has 2 divisors, whose sum is σ = 66943622. Its totient is φ = 66943620.

The previous prime is 66943607. The next prime is 66943627. The reversal of 66943621 is 12634966.

66943621 = T₆₆₇₉ + T₆₆₈₀ + T₆₆₈₁.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51624225 + 15319396 = 7185^2 + 3914^2 .

It is a cyclic number.

It is not a de Polignac number, because 66943621 - 2⁵ = 66943589 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66943627) 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, 33471810 + 33471811.

It is an arithmetic number, because the mean of its divisors is an integer number (33471811).

Almost surely, 2^66943621 is an apocalyptic number.

66943621 is the 6681-st centered triangular number.

It is an amenable number.

66943621 is a deficient number, since it is larger than the sum of its proper divisors (1).

66943621 is an equidigital number, since it uses as much as digits as its factorization.

66943621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 46656, while the sum is 37.

The square root of 66943621 is about 8181.9081515255. The cubic root of 66943621 is about 406.0408546817.

The spelling of 66943621 in words is "sixty-six million, nine hundred forty-three thousand, six hundred twenty-one".