6400 has 27 divisors (see below), whose sum is σ = 15841. Its totient is φ = 2560.

The previous prime is 6397. The next prime is 6421. The reversal of 6400 is 46.

6400 = T₇₉ + T₈₀.

The square root of 6400 is 80.

It is a perfect power (a square), and thus also a powerful number.

6400 is nontrivially palindromic in base 7.

It can be written as a sum of positive squares in only one way, i.e., 2304 + 4096 = 48^2 + 64^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a Duffinian number.

It is a plaindrome in base 11.

It is a nialpdrome in base 10.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (3) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 1278 + ... + 1282.

2⁶⁴⁰⁰ is an apocalyptic number.

6400 is the 80-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6400

6400 is an abundant number, since it is smaller than the sum of its proper divisors (9441).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6400 is an equidigital number, since it uses as much as digits as its factorization.

6400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26 (or 7 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 10.

The cubic root of 6400 is about 18.5663553345.

Multiplying 6400 by its sum of digits (10), we get a cube (64000 = 40³).

Adding to 6400 its reverse (46), we get a palindrome (6446).

It can be divided in two parts, 6 and 400, that added together give a triangular number (406 = T₂₈).

The spelling of 6400 in words is "six thousand, four hundred".