398438666 has 4 divisors (see below), whose sum is σ = 597658002. Its totient is φ = 199219332.

The previous prime is 398438647. The next prime is 398438713. The reversal of 398438666 is 666834893.

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

It can be written as a sum of positive squares in only one way, i.e., 395811025 + 2627641 = 19895^2 + 1621^2 .

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 as a sum of consecutive naturals, namely, 99609665 + ... + 99609668.

Almost surely, 2^398438666 is an apocalyptic number.

398438666 is a deficient number, since it is larger than the sum of its proper divisors (199219336).

398438666 is a wasteful number, since it uses less digits than its factorization.

398438666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199219335.

The product of its digits is 4478976, while the sum is 53.

The square root of 398438666 is about 19960.9284854187. The cubic root of 398438666 is about 735.8463824103.

The spelling of 398438666 in words is "three hundred ninety-eight million, four hundred thirty-eight thousand, six hundred sixty-six".