66716569 has 2 divisors, whose sum is σ = 66716570. Its totient is φ = 66716568.

The previous prime is 66716567. The next prime is 66716579. The reversal of 66716569 is 96561766.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 65804544 + 912025 = 8112^2 + 955^2 .

It is a cyclic number.

It is not a de Polignac number, because 66716569 - 2¹ = 66716567 is a prime.

It is a super-2 number, since 2×66716569² = 8902201158263522, which contains 22 as substring.

Together with 66716567, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (66716561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33358284 + 33358285.

It is an arithmetic number, because the mean of its divisors is an integer number (33358285).

Almost surely, 2^66716569 is an apocalyptic number.

It is an amenable number.

66716569 is a deficient number, since it is larger than the sum of its proper divisors (1).

66716569 is an equidigital number, since it uses as much as digits as its factorization.

66716569 is an evil number, because the sum of its binary digits is even.

The product of its digits is 408240, while the sum is 46.

The square root of 66716569 is about 8168.0211189737. The cubic root of 66716569 is about 405.5812798289.

The spelling of 66716569 in words is "sixty-six million, seven hundred sixteen thousand, five hundred sixty-nine".