1998157 has 4 divisors (see below), whose sum is σ = 2283616. Its totient is φ = 1712700.

The previous prime is 1998133. The next prime is 1998169. The reversal of 1998157 is 7518991.

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, and also an emirpimes, since its reverse is a distinct semiprime: 7518991 = 1171 ⋅6421.

It is a cyclic number.

It is not a de Polignac number, because 1998157 - 2¹¹ = 1996109 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 (1998107) 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, 142719 + ... + 142732.

It is an arithmetic number, because the mean of its divisors is an integer number (570904).

2^1998157 is an apocalyptic number.

It is an amenable number.

1998157 is a deficient number, since it is larger than the sum of its proper divisors (285459).

1998157 is an equidigital number, since it uses as much as digits as its factorization.

1998157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 285458.

The product of its digits is 22680, while the sum is 40.

The square root of 1998157 is about 1413.5618132929. The cubic root of 1998157 is about 125.9533925210.

The spelling of 1998157 in words is "one million, nine hundred ninety-eight thousand, one hundred fifty-seven".