6399561 has 32 divisors (see below), whose sum is σ = 10531840. Its totient is φ = 3374784.

The previous prime is 6399551. The next prime is 6399577. The reversal of 6399561 is 1659936.

It is not a de Polignac number, because 6399561 - 2⁷ = 6399433 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6399511) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16971 + ... + 17343.

It is an arithmetic number, because the mean of its divisors is an integer number (329120).

Almost surely, 2^6399561 is an apocalyptic number.

It is an amenable number.

6399561 is a deficient number, since it is larger than the sum of its proper divisors (4132279).

6399561 is a wasteful number, since it uses less digits than its factorization.

6399561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445.

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

The square root of 6399561 is about 2529.7353616535. The cubic root of 6399561 is about 185.6593081277.

The spelling of 6399561 in words is "six million, three hundred ninety-nine thousand, five hundred sixty-one".