399649 has 4 divisors (see below), whose sum is σ = 413460. Its totient is φ = 385840.

The previous prime is 399647. The next prime is 399667. The reversal of 399649 is 946993.

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

It can be written as a sum of positive squares in 2 ways, for example, as 219024 + 180625 = 468^2 + 425^2 .

It is a cyclic number.

It is not a de Polignac number, because 399649 - 2¹ = 399647 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (399643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6862 + ... + 6919.

It is an arithmetic number, because the mean of its divisors is an integer number (103365).

2³⁹⁹⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

399649 is a deficient number, since it is larger than the sum of its proper divisors (13811).

399649 is a wasteful number, since it uses less digits than its factorization.

399649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13810.

The product of its digits is 52488, while the sum is 40.

The square root of 399649 is about 632.1779812679. The cubic root of 399649 is about 73.6590720816.

The spelling of 399649 in words is "three hundred ninety-nine thousand, six hundred forty-nine".