6427991 has 4 divisors (see below), whose sum is σ = 6537000. Its totient is φ = 6318984.

The previous prime is 6427987. The next prime is 6428011. The reversal of 6427991 is 1997246.

6427991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1997246 = 2 ⋅998623.

It is a cyclic number.

It is not a de Polignac number, because 6427991 - 2² = 6427987 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 (6427931) 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 3 ways as a sum of consecutive naturals, for example, 54416 + ... + 54533.

It is an arithmetic number, because the mean of its divisors is an integer number (1634250).

Almost surely, 2^6427991 is an apocalyptic number.

6427991 is a deficient number, since it is larger than the sum of its proper divisors (109009).

6427991 is a wasteful number, since it uses less digits than its factorization.

6427991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109008.

The product of its digits is 27216, while the sum is 38.

The square root of 6427991 is about 2535.3482995439. The cubic root of 6427991 is about 185.9338320158.

The spelling of 6427991 in words is "six million, four hundred twenty-seven thousand, nine hundred ninety-one".