6391021 has 24 divisors (see below), whose sum is σ = 8171520. Its totient is φ = 4953312.

The previous prime is 6391009. The next prime is 6391043. The reversal of 6391021 is 1201936.

It is not a de Polignac number, because 6391021 - 2⁷ = 6390893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6390983 and 6391001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6391061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50260 + ... + 50386.

It is an arithmetic number, because the mean of its divisors is an integer number (340480).

Almost surely, 2^6391021 is an apocalyptic number.

It is an amenable number.

6391021 is a deficient number, since it is larger than the sum of its proper divisors (1780499).

6391021 is a wasteful number, since it uses less digits than its factorization.

6391021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233 (or 226 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 6391021 is about 2528.0468745654. The cubic root of 6391021 is about 185.5766859867.

Adding to 6391021 its reverse (1201936), we get a palindrome (7592957).

The spelling of 6391021 in words is "six million, three hundred ninety-one thousand, twenty-one".