6720391 has 4 divisors (see below), whose sum is σ = 6729984. Its totient is φ = 6710800.

The previous prime is 6720383. The next prime is 6720403. The reversal of 6720391 is 1930276.

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

It is a cyclic number.

It is not a de Polignac number, because 6720391 - 2³ = 6720383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6720331) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3655 + ... + 5176.

It is an arithmetic number, because the mean of its divisors is an integer number (1682496).

Almost surely, 2^6720391 is an apocalyptic number.

6720391 is a deficient number, since it is larger than the sum of its proper divisors (9593).

6720391 is an equidigital number, since it uses as much as digits as its factorization.

6720391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9592.

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 6720391 is about 2592.3716940285. The cubic root of 6720391 is about 188.7114190987.

The spelling of 6720391 in words is "six million, seven hundred twenty thousand, three hundred ninety-one".