66671617 has 4 divisors (see below), whose sum is σ = 68297796. Its totient is φ = 65045440.

The previous prime is 66671611. The next prime is 66671621. The reversal of 66671617 is 71617666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 71617666 = 2 ⋅35808833.

It can be written as a sum of positive squares in 2 ways, for example, as 4198401 + 62473216 = 2049^2 + 7904^2 .

It is a cyclic number.

It is not a de Polignac number, because 66671617 - 2¹¹ = 66669569 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66671617.

It is not an unprimeable number, because it can be changed into a prime (66671611) 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, 813028 + ... + 813109.

It is an arithmetic number, because the mean of its divisors is an integer number (17074449).

Almost surely, 2^66671617 is an apocalyptic number.

It is an amenable number.

66671617 is a deficient number, since it is larger than the sum of its proper divisors (1626179).

66671617 is a wasteful number, since it uses less digits than its factorization.

66671617 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1626178.

The product of its digits is 63504, while the sum is 40.

The square root of 66671617 is about 8165.2689484180. The cubic root of 66671617 is about 405.4901690989.

The spelling of 66671617 in words is "sixty-six million, six hundred seventy-one thousand, six hundred seventeen".