398823901978 has 4 divisors (see below), whose sum is σ = 598235852970. Its totient is φ = 199411950988.

The previous prime is 398823901921. The next prime is 398823901981. The reversal of 398823901978 is 879109328893.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 879109328893 = 19 ⋅46268912047.

It can be written as a sum of positive squares in only one way, i.e., 263438907169 + 135384994809 = 513263^2 + 367947^2 .

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99705975493 + ... + 99705975496.

Almost surely, 2^398823901978 is an apocalyptic number.

398823901978 is a deficient number, since it is larger than the sum of its proper divisors (199411950992).

398823901978 is a wasteful number, since it uses less digits than its factorization.

398823901978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199411950991.

The product of its (nonzero) digits is 47029248, while the sum is 67.

The spelling of 398823901978 in words is "three hundred ninety-eight billion, eight hundred twenty-three million, nine hundred one thousand, nine hundred seventy-eight".