1998655 has 4 divisors (see below), whose sum is σ = 2398392. Its totient is φ = 1598920.

The previous prime is 1998643. The next prime is 1998679. The reversal of 1998655 is 5568991.

1998655 = 358² + 359² + ... + 372².

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5568991 = 227 ⋅24533.

It is not a de Polignac number, because 1998655 - 2⁷ = 1998527 is a prime.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a zygodrome in base 2.

It is a congruent number.

It is an unprimeable number.

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, 199861 + ... + 199870.

It is an arithmetic number, because the mean of its divisors is an integer number (599598).

2^1998655 is an apocalyptic number.

1998655 is a deficient number, since it is larger than the sum of its proper divisors (399737).

1998655 is an equidigital number, since it uses as much as digits as its factorization.

1998655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399736.

The product of its digits is 97200, while the sum is 43.

The square root of 1998655 is about 1413.7379530875. The cubic root of 1998655 is about 125.9638554257.

The spelling of 1998655 in words is "one million, nine hundred ninety-eight thousand, six hundred fifty-five".