6440855 has 4 divisors (see below), whose sum is σ = 7729032. Its totient is φ = 5152680.

The previous prime is 6440831. The next prime is 6440873. The reversal of 6440855 is 5580446.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5580446 = 2 ⋅2790223.

It is not a de Polignac number, because 6440855 - 2¹⁶ = 6375319 is a prime.

It is a super-2 number, since 2×6440855² = 82969226262050, which contains 22 as substring.

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, 644081 + ... + 644090.

It is an arithmetic number, because the mean of its divisors is an integer number (1932258).

Almost surely, 2^6440855 is an apocalyptic number.

6440855 is a deficient number, since it is larger than the sum of its proper divisors (1288177).

6440855 is a wasteful number, since it uses less digits than its factorization.

6440855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1288176.

The product of its (nonzero) digits is 19200, while the sum is 32.

The square root of 6440855 is about 2537.8839610983. The cubic root of 6440855 is about 186.0577825639.

The spelling of 6440855 in words is "six million, four hundred forty thousand, eight hundred fifty-five".