66766421 has 2 divisors, whose sum is σ = 66766422. Its totient is φ = 66766420.

The previous prime is 66766411. The next prime is 66766451. The reversal of 66766421 is 12466766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 47748100 + 19018321 = 6910^2 + 4361^2 .

It is a cyclic number.

It is not a de Polignac number, because 66766421 - 2²² = 62572117 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 (66766411) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33383210 + 33383211.

It is an arithmetic number, because the mean of its divisors is an integer number (33383211).

Almost surely, 2^66766421 is an apocalyptic number.

It is an amenable number.

66766421 is a deficient number, since it is larger than the sum of its proper divisors (1).

66766421 is an equidigital number, since it uses as much as digits as its factorization.

66766421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 38.

The square root of 66766421 is about 8171.0722062652. The cubic root of 66766421 is about 405.6822742512.

The spelling of 66766421 in words is "sixty-six million, seven hundred sixty-six thousand, four hundred twenty-one".