398686861 has 4 divisors (see below), whose sum is σ = 419670400. Its totient is φ = 377703324.

The previous prime is 398686819. The next prime is 398686901. The reversal of 398686861 is 168686893.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 398686861 - 2⁷ = 398686733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (398686801) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 10491741 + ... + 10491778.

It is an arithmetic number, because the mean of its divisors is an integer number (104917600).

Almost surely, 2^398686861 is an apocalyptic number.

It is an amenable number.

398686861 is a deficient number, since it is larger than the sum of its proper divisors (20983539).

398686861 is a wasteful number, since it uses less digits than its factorization.

398686861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20983538.

The product of its digits is 2985984, while the sum is 55.

The square root of 398686861 is about 19967.1445379654. The cubic root of 398686861 is about 735.9991415839. Note that the first 3 decimals are identical.

The spelling of 398686861 in words is "three hundred ninety-eight million, six hundred eighty-six thousand, eight hundred sixty-one".