66789517 has 2 divisors, whose sum is σ = 66789518. Its totient is φ = 66789516.

The previous prime is 66789497. The next prime is 66789577. The reversal of 66789517 is 71598766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 34821801 + 31967716 = 5901^2 + 5654^2 .

It is a cyclic number.

It is not a de Polignac number, because 66789517 - 2¹⁵ = 66756749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66789577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33394758 + 33394759.

It is an arithmetic number, because the mean of its divisors is an integer number (33394759).

Almost surely, 2^66789517 is an apocalyptic number.

It is an amenable number.

66789517 is a deficient number, since it is larger than the sum of its proper divisors (1).

66789517 is an equidigital number, since it uses as much as digits as its factorization.

66789517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 635040, while the sum is 49.

The square root of 66789517 is about 8172.4853624831. The cubic root of 66789517 is about 405.7290470525.

Subtracting 66789517 from its reverse (71598766), we obtain a square (4809249 = 2193²).

The spelling of 66789517 in words is "sixty-six million, seven hundred eighty-nine thousand, five hundred seventeen".