1998765 has 12 divisors (see below), whose sum is σ = 3464604. Its totient is φ = 1065984.

The previous prime is 1998761. The next prime is 1998793. The reversal of 1998765 is 5678991.

It can be written as a sum of positive squares in 2 ways, for example, as 311364 + 1687401 = 558^2 + 1299^2 .

It is not a de Polignac number, because 1998765 - 2² = 1998761 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 44417 = 1998765 / (1 + 9 + 9 + 8 + 7 + 6 + 5).

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 1998765.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1998761) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 22164 + ... + 22253.

It is an arithmetic number, because the mean of its divisors is an integer number (288717).

2^1998765 is an apocalyptic number.

1998765 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1998765 is a deficient number, since it is larger than the sum of its proper divisors (1465839).

1998765 is a wasteful number, since it uses less digits than its factorization.

1998765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44428 (or 44425 counting only the distinct ones).

The product of its digits is 136080, while the sum is 45.

The square root of 1998765 is about 1413.7768565088. The cubic root of 1998765 is about 125.9661662748.

The spelling of 1998765 in words is "one million, nine hundred ninety-eight thousand, seven hundred sixty-five".