6399729 has 20 divisors (see below), whose sum is σ = 10926784. Its totient is φ = 3656664.

The previous prime is 6399719. The next prime is 6399737. The reversal of 6399729 is 9279936.

6399729 is a `hidden beast` number, since 639 + 9 + 7 + 2 + 9 = 666.

It is not a de Polignac number, because 6399729 - 2¹³ = 6391537 is a prime.

It is a super-4 number, since 4×6399729⁴ (a number of 28 digits) contains 4444 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6399709) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 5077 + ... + 6210.

Almost surely, 2^6399729 is an apocalyptic number.

It is an amenable number.

6399729 is a deficient number, since it is larger than the sum of its proper divisors (4527055).

6399729 is a wasteful number, since it uses less digits than its factorization.

6399729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11306 (or 11297 counting only the distinct ones).

The product of its digits is 183708, while the sum is 45.

The square root of 6399729 is about 2529.7685664898. The cubic root of 6399729 is about 185.6609327438.

The spelling of 6399729 in words is "six million, three hundred ninety-nine thousand, seven hundred twenty-nine".