6391621 has 8 divisors (see below), whose sum is σ = 6519744. Its totient is φ = 6264960.

The previous prime is 6391607. The next prime is 6391663. The reversal of 6391621 is 1261936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6391621 - 2⁵ = 6391589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6391621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6391601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12456 + ... + 12958.

It is an arithmetic number, because the mean of its divisors is an integer number (814968).

Almost surely, 2^6391621 is an apocalyptic number.

It is an amenable number.

6391621 is a deficient number, since it is larger than the sum of its proper divisors (128123).

6391621 is a wasteful number, since it uses less digits than its factorization.

6391621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 731.

The product of its digits is 1944, while the sum is 28.

The square root of 6391621 is about 2528.1655404661. The cubic root of 6391621 is about 185.5824932240.

The spelling of 6391621 in words is "six million, three hundred ninety-one thousand, six hundred twenty-one".