66706621 has 2 divisors, whose sum is σ = 66706622. Its totient is φ = 66706620.

The previous prime is 66706603. The next prime is 66706643. The reversal of 66706621 is 12660766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46104100 + 20602521 = 6790^2 + 4539^2 .

It is a cyclic number.

It is not a de Polignac number, because 66706621 - 2¹⁷ = 66575549 is a prime.

It is equal to p_3935536 and since 66706621 and 3935536 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66706121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33353310 + 33353311.

It is an arithmetic number, because the mean of its divisors is an integer number (33353311).

Almost surely, 2^66706621 is an apocalyptic number.

It is an amenable number.

66706621 is a deficient number, since it is larger than the sum of its proper divisors (1).

66706621 is an equidigital number, since it uses as much as digits as its factorization.

66706621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 66706621 is about 8167.4121360441. The cubic root of 66706621 is about 405.5611203034.

The spelling of 66706621 in words is "sixty-six million, seven hundred six thousand, six hundred twenty-one".