398978 has 4 divisors (see below), whose sum is σ = 598470. Its totient is φ = 199488.

The previous prime is 398977. The next prime is 398989. The reversal of 398978 is 879893.

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., 332929 + 66049 = 577^2 + 257^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (398977) 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 as a sum of consecutive naturals, namely, 99743 + ... + 99746.

2³⁹⁸⁹⁷⁸ is an apocalyptic number.

398978 is a deficient number, since it is larger than the sum of its proper divisors (199492).

398978 is a wasteful number, since it uses less digits than its factorization.

398978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199491.

The product of its digits is 108864, while the sum is 44.

The square root of 398978 is about 631.6470533455. The cubic root of 398978 is about 73.6178251171.

The spelling of 398978 in words is "three hundred ninety-eight thousand, nine hundred seventy-eight".