66416321 has 4 divisors (see below), whose sum is σ = 66783444. Its totient is φ = 66049200.

The previous prime is 66416309. The next prime is 66416333. The reversal of 66416321 is 12361466.

It is a happy number.

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

It is an interprime number because it is at equal distance from previous prime (66416309) and next prime (66416333).

It can be written as a sum of positive squares in 2 ways, for example, as 11122225 + 55294096 = 3335^2 + 7436^2 .

It is a cyclic number.

It is not a de Polignac number, because 66416321 - 2¹⁸ = 66154177 is a prime.

It is a super-2 number, since 2×66416321² = 8822255390350082, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (66416821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 183290 + ... + 183651.

It is an arithmetic number, because the mean of its divisors is an integer number (16695861).

Almost surely, 2^66416321 is an apocalyptic number.

It is an amenable number.

66416321 is a deficient number, since it is larger than the sum of its proper divisors (367123).

66416321 is a wasteful number, since it uses less digits than its factorization.

66416321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367122.

The product of its digits is 5184, while the sum is 29.

The square root of 66416321 is about 8149.6209114289. The cubic root of 66416321 is about 404.9719454224.

Adding to 66416321 its reverse (12361466), we get a palindrome (78777787).

The spelling of 66416321 in words is "sixty-six million, four hundred sixteen thousand, three hundred twenty-one".