66768521 has 2 divisors, whose sum is σ = 66768522. Its totient is φ = 66768520.

The previous prime is 66768467. The next prime is 66768523. The reversal of 66768521 is 12586766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42758521 + 24010000 = 6539^2 + 4900^2 .

It is a cyclic number.

It is not a de Polignac number, because 66768521 - 2¹⁰ = 66767497 is a prime.

Together with 66768523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66768523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33384260 + 33384261.

It is an arithmetic number, because the mean of its divisors is an integer number (33384261).

Almost surely, 2^66768521 is an apocalyptic number.

It is an amenable number.

66768521 is a deficient number, since it is larger than the sum of its proper divisors (1).

66768521 is an equidigital number, since it uses as much as digits as its factorization.

66768521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120960, while the sum is 41.

The square root of 66768521 is about 8171.2007073624. The cubic root of 66768521 is about 405.6865275062.

The spelling of 66768521 in words is "sixty-six million, seven hundred sixty-eight thousand, five hundred twenty-one".