398438665 has 16 divisors (see below), whose sum is σ = 483440400. Its totient is φ = 315228160.

The previous prime is 398438647. The next prime is 398438713. The reversal of 398438665 is 566834893.

It can be written as a sum of positive squares in 8 ways, for example, as 156816 + 398281849 = 396^2 + 19957^2 .

It is not a de Polignac number, because 398438665 - 2²⁷ = 264220937 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190425 + ... + 192505.

It is an arithmetic number, because the mean of its divisors is an integer number (30215025).

Almost surely, 2^398438665 is an apocalyptic number.

It is an amenable number.

398438665 is a deficient number, since it is larger than the sum of its proper divisors (85001735).

398438665 is a wasteful number, since it uses less digits than its factorization.

398438665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2492.

The product of its digits is 3732480, while the sum is 52.

The square root of 398438665 is about 19960.9284603698. The cubic root of 398438665 is about 735.8463817947.

The spelling of 398438665 in words is "three hundred ninety-eight million, four hundred thirty-eight thousand, six hundred sixty-five".