66616213 has 4 divisors (see below), whose sum is σ = 66687948. Its totient is φ = 66544480.

The previous prime is 66616201. The next prime is 66616259. The reversal of 66616213 is 31261666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17363889 + 49252324 = 4167^2 + 7018^2 .

It is a cyclic number.

It is not a de Polignac number, because 66616213 - 2¹³ = 66608021 is a prime.

It is a super-2 number, since 2×66616213² = 8875439668922738, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66616313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34456 + ... + 36337.

It is an arithmetic number, because the mean of its divisors is an integer number (16671987).

Almost surely, 2^66616213 is an apocalyptic number.

It is an amenable number.

66616213 is a deficient number, since it is larger than the sum of its proper divisors (71735).

66616213 is an equidigital number, since it uses as much as digits as its factorization.

66616213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71734.

The product of its digits is 7776, while the sum is 31.

The square root of 66616213 is about 8161.8755810169. The cubic root of 66616213 is about 405.3778174255.

Adding to 66616213 its reverse (31261666), we get a palindrome (97877879).

The spelling of 66616213 in words is "sixty-six million, six hundred sixteen thousand, two hundred thirteen".