66724517 has 2 divisors, whose sum is σ = 66724518. Its totient is φ = 66724516.

The previous prime is 66724477. The next prime is 66724531. The reversal of 66724517 is 71542766.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66569281 + 155236 = 8159^2 + 394^2 .

It is a cyclic number.

It is not a de Polignac number, because 66724517 - 2⁶ = 66724453 is a prime.

It is a super-2 number, since 2×66724517² = 8904322337766578, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66724547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33362258 + 33362259.

It is an arithmetic number, because the mean of its divisors is an integer number (33362259).

Almost surely, 2^66724517 is an apocalyptic number.

It is an amenable number.

66724517 is a deficient number, since it is larger than the sum of its proper divisors (1).

66724517 is an equidigital number, since it uses as much as digits as its factorization.

66724517 is an evil number, because the sum of its binary digits is even.

The product of its digits is 70560, while the sum is 38.

The square root of 66724517 is about 8168.5076360373. The cubic root of 66724517 is about 405.5973849337.

The spelling of 66724517 in words is "sixty-six million, seven hundred twenty-four thousand, five hundred seventeen".