1981759 has 4 divisors (see below), whose sum is σ = 2134216. Its totient is φ = 1829304.

The previous prime is 1981753. The next prime is 1981787. The reversal of 1981759 is 9571891.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1981759 - 2⁷ = 1981631 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 (1981753) 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, 76209 + ... + 76234.

It is an arithmetic number, because the mean of its divisors is an integer number (533554).

2^1981759 is an apocalyptic number.

1981759 is a deficient number, since it is larger than the sum of its proper divisors (152457).

1981759 is a wasteful number, since it uses less digits than its factorization.

1981759 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 152456.

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

The square root of 1981759 is about 1407.7496226247. The cubic root of 1981759 is about 125.6078975588.

The spelling of 1981759 in words is "one million, nine hundred eighty-one thousand, seven hundred fifty-nine".