6421865 has 4 divisors (see below), whose sum is σ = 7706244. Its totient is φ = 5137488.

The previous prime is 6421843. The next prime is 6421873. The reversal of 6421865 is 5681246.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2128681 + 4293184 = 1459^2 + 2072^2 .

It is a cyclic number.

It is not a de Polignac number, because 6421865 - 2¹⁸ = 6159721 is a prime.

It is a Duffinian number.

It is a Curzon 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, 642182 + ... + 642191.

It is an arithmetic number, because the mean of its divisors is an integer number (1926561).

Almost surely, 2^6421865 is an apocalyptic number.

It is an amenable number.

6421865 is a deficient number, since it is larger than the sum of its proper divisors (1284379).

6421865 is a wasteful number, since it uses less digits than its factorization.

6421865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1284378.

The product of its digits is 11520, while the sum is 32.

The square root of 6421865 is about 2534.1398935339. The cubic root of 6421865 is about 185.8747470603.

The spelling of 6421865 in words is "six million, four hundred twenty-one thousand, eight hundred sixty-five".