6399651 has 4 divisors (see below), whose sum is σ = 8532872. Its totient is φ = 4266432.

The previous prime is 6399643. The next prime is 6399677. The reversal of 6399651 is 1569936.

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

It is not a de Polignac number, because 6399651 - 2³ = 6399643 is a prime.

It is a D-number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6399611) 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, 1066606 + ... + 1066611.

It is an arithmetic number, because the mean of its divisors is an integer number (2133218).

Almost surely, 2^6399651 is an apocalyptic number.

6399651 is a deficient number, since it is larger than the sum of its proper divisors (2133221).

6399651 is a wasteful number, since it uses less digits than its factorization.

6399651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2133220.

The product of its digits is 43740, while the sum is 39.

The square root of 6399651 is about 2529.7531500129. The cubic root of 6399651 is about 185.6601784613.

The spelling of 6399651 in words is "six million, three hundred ninety-nine thousand, six hundred fifty-one".