1998751 has 4 divisors (see below), whose sum is σ = 2002600. Its totient is φ = 1994904.

The previous prime is 1998739. The next prime is 1998761. The reversal of 1998751 is 1578991.

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: 1578991 = 127 ⋅12433.

It is a cyclic number.

It is not a de Polignac number, because 1998751 - 2¹³ = 1990559 is a prime.

It is a super-4 number, since 4×1998751⁴ (a number of 26 digits) contains 4444 as substring.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998701) 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, 996 + ... + 2233.

It is an arithmetic number, because the mean of its divisors is an integer number (500650).

2^1998751 is an apocalyptic number.

1998751 is a deficient number, since it is larger than the sum of its proper divisors (3849).

1998751 is an equidigital number, since it uses as much as digits as its factorization.

1998751 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3848.

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

The square root of 1998751 is about 1413.7719052238. The cubic root of 1998751 is about 125.9658721714.

The spelling of 1998751 in words is "one million, nine hundred ninety-eight thousand, seven hundred fifty-one".