6401 has 4 divisors (see below), whose sum is σ = 6612. Its totient is φ = 6192.

The previous prime is 6397. The next prime is 6421. The reversal of 6401 is 1046.

It is a Cunningham number, because it is equal to 80²+1.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1046 = 2 ⋅523.

It can be written as a sum of positive squares in 2 ways, for example, as 5776 + 625 = 76^2 + 25^2 .

It is a cyclic number.

It is not a de Polignac number, because 6401 - 2² = 6397 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (6421) 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, 50 + ... + 123.

It is an arithmetic number, because the mean of its divisors is an integer number (1653).

It is a Proth number, since it is equal to 25 ⋅ 2⁸ + 1 and 25 < 2⁸.

2⁶⁴⁰¹ is an apocalyptic number.

It is an amenable number.

6401 is a deficient number, since it is larger than the sum of its proper divisors (211).

6401 is a wasteful number, since it uses less digits than its factorization.

6401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 210.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 6401 is about 80.0062497559. The cubic root of 6401 is about 18.5673222818.

Adding to 6401 its reverse (1046), we get a palindrome (7447).

The spelling of 6401 in words is "six thousand, four hundred one".