6440255 has 4 divisors (see below), whose sum is σ = 7728312. Its totient is φ = 5152200.

The previous prime is 6440249. The next prime is 6440303. The reversal of 6440255 is 5520446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5520446 = 2 ⋅2760223.

It is not a de Polignac number, because 6440255 - 2⁶ = 6440191 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 644021 + ... + 644030.

It is an arithmetic number, because the mean of its divisors is an integer number (1932078).

Almost surely, 2^6440255 is an apocalyptic number.

6440255 is a deficient number, since it is larger than the sum of its proper divisors (1288057).

6440255 is a wasteful number, since it uses less digits than its factorization.

6440255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288056.

The product of its (nonzero) digits is 4800, while the sum is 26.

The square root of 6440255 is about 2537.7657496310. The cubic root of 6440255 is about 186.0520049595.

The spelling of 6440255 in words is "six million, four hundred forty thousand, two hundred fifty-five".