398687973891 has 4 divisors (see below), whose sum is σ = 531583965192. Its totient is φ = 265791982592.

The previous prime is 398687973889. The next prime is 398687973911. The reversal of 398687973891 is 198379786893.

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

It is a cyclic number.

It is not a de Polignac number, because 398687973891 - 2¹ = 398687973889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (398687973391) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66447995646 + ... + 66447995651.

It is an arithmetic number, because the mean of its divisors is an integer number (132895991298).

Almost surely, 2^398687973891 is an apocalyptic number.

398687973891 is a deficient number, since it is larger than the sum of its proper divisors (132895991301).

398687973891 is a wasteful number, since it uses less digits than its factorization.

398687973891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132895991300.

The product of its digits is 987614208, while the sum is 78.

The spelling of 398687973891 in words is "three hundred ninety-eight billion, six hundred eighty-seven million, nine hundred seventy-three thousand, eight hundred ninety-one".