1998857 has 18 divisors (see below), whose sum is σ = 2475738. Its totient is φ = 1608768.

The previous prime is 1998839. The next prime is 1998881. The reversal of 1998857 is 7588991.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1132096 + 866761 = 1064^2 + 931^2 .

It is not a de Polignac number, because 1998857 - 2⁶ = 1998793 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (1998817) 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 in 17 ways as a sum of consecutive naturals, for example, 17633 + ... + 17745.

It is an arithmetic number, because the mean of its divisors is an integer number (137541).

2^1998857 is an apocalyptic number.

It is an amenable number.

1998857 is a deficient number, since it is larger than the sum of its proper divisors (476881).

1998857 is a wasteful number, since it uses less digits than its factorization.

1998857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165 (or 139 counting only the distinct ones).

The product of its digits is 181440, while the sum is 47.

The square root of 1998857 is about 1413.8093930937. The cubic root of 1998857 is about 125.9680989197.

The spelling of 1998857 in words is "one million, nine hundred ninety-eight thousand, eight hundred fifty-seven".