6399971 has 2 divisors, whose sum is σ = 6399972. Its totient is φ = 6399970.

The previous prime is 6399961. The next prime is 6400013. The reversal of 6399971 is 1799936.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6399971 - 2¹⁸ = 6137827 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6399931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3199985 + 3199986.

It is an arithmetic number, because the mean of its divisors is an integer number (3199986).

Almost surely, 2^6399971 is an apocalyptic number.

6399971 is a deficient number, since it is larger than the sum of its proper divisors (1).

6399971 is an equidigital number, since it uses as much as digits as its factorization.

6399971 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 91854, while the sum is 44.

The square root of 6399971 is about 2529.8163965000. The cubic root of 6399971 is about 185.6632729148.

The spelling of 6399971 in words is "six million, three hundred ninety-nine thousand, nine hundred seventy-one".