6421665 has 16 divisors (see below), whose sum is σ = 10879488. Its totient is φ = 3223296.

The previous prime is 6421643. The next prime is 6421697. The reversal of 6421665 is 5661246.

6421665 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 6421665 - 2¹² = 6417569 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12337 + ... + 12846.

It is an arithmetic number, because the mean of its divisors is an integer number (679968).

Almost surely, 2^6421665 is an apocalyptic number.

It is an amenable number.

6421665 is a deficient number, since it is larger than the sum of its proper divisors (4457823).

6421665 is a wasteful number, since it uses less digits than its factorization.

6421665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25208.

The product of its digits is 8640, while the sum is 30.

The square root of 6421665 is about 2534.1004321060. The cubic root of 6421665 is about 185.8728174373.

The spelling of 6421665 in words is "six million, four hundred twenty-one thousand, six hundred sixty-five".