66641 has 4 divisors (see below), whose sum is σ = 67392. Its totient is φ = 65892.

The previous prime is 66629. The next prime is 66643. The reversal of 66641 is 14666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 14666 = 2 ⋅7333.

It is a cyclic number.

It is not a de Polignac number, because 66641 - 2¹⁰ = 65617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a nialpdrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (66643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 221 + ... + 426.

It is an arithmetic number, because the mean of its divisors is an integer number (16848).

2⁶⁶⁶⁴¹ is an apocalyptic number.

It is an amenable number.

66641 is a deficient number, since it is larger than the sum of its proper divisors (751).

66641 is a wasteful number, since it uses less digits than its factorization.

66641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 750.

The product of its digits is 864, while the sum is 23.

The square root of 66641 is about 258.1491816760. The cubic root of 66641 is about 40.5428089742.

It can be divided in two parts, 666 and 41, that added together give a palindrome (707).

The spelling of 66641 in words is "sixty-six thousand, six hundred forty-one".