6390021 has 16 divisors (see below), whose sum is σ = 9699840. Its totient is φ = 3703920.

The previous prime is 6390001. The next prime is 6390029. The reversal of 6390021 is 1200936.

It is not a de Polignac number, because 6390021 - 2⁵ = 6389989 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6390021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6390029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3451 + ... + 4968.

It is an arithmetic number, because the mean of its divisors is an integer number (606240).

Almost surely, 2^6390021 is an apocalyptic number.

It is an amenable number.

6390021 is a deficient number, since it is larger than the sum of its proper divisors (3309819).

6390021 is a wasteful number, since it uses less digits than its factorization.

6390021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8456.

The product of its (nonzero) digits is 324, while the sum is 21.

The square root of 6390021 is about 2527.8490856853. The cubic root of 6390021 is about 185.5670064500.

Adding to 6390021 its reverse (1200936), we get a palindrome (7590957).

The spelling of 6390021 in words is "six million, three hundred ninety thousand, twenty-one".