66401 has 4 divisors (see below), whose sum is σ = 69312. Its totient is φ = 63492.

The previous prime is 66383. The next prime is 66403. The reversal of 66401 is 10466.

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 an emirpimes, since its reverse is a distinct semiprime: 10466 = 2 ⋅5233.

It is a cyclic number.

It is not a de Polignac number, because 66401 - 2⁶ = 66337 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 66401.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 66401.

It is not an unprimeable number, because it can be changed into a prime (66403) 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, 1421 + ... + 1466.

It is an arithmetic number, because the mean of its divisors is an integer number (17328).

2⁶⁶⁴⁰¹ is an apocalyptic number.

It is an amenable number.

66401 is a deficient number, since it is larger than the sum of its proper divisors (2911).

66401 is a wasteful number, since it uses less digits than its factorization.

66401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2910.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 66401 is about 257.6839149035. The cubic root of 66401 is about 40.4940803216.

Adding to 66401 its reverse (10466), we get a palindrome (76867).

The spelling of 66401 in words is "sixty-six thousand, four hundred one".