1981589 has 2 divisors, whose sum is σ = 1981590. Its totient is φ = 1981588.

The previous prime is 1981583. The next prime is 1981597. The reversal of 1981589 is 9851891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1800964 + 180625 = 1342^2 + 425^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1981589 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1981583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 990794 + 990795.

It is an arithmetic number, because the mean of its divisors is an integer number (990795).

2^1981589 is an apocalyptic number.

It is an amenable number.

1981589 is a deficient number, since it is larger than the sum of its proper divisors (1).

1981589 is an equidigital number, since it uses as much as digits as its factorization.

1981589 is an evil number, because the sum of its binary digits is even.

The product of its digits is 25920, while the sum is 41.

The square root of 1981589 is about 1407.6892412745. The cubic root of 1981589 is about 125.6043058080.

The spelling of 1981589 in words is "one million, nine hundred eighty-one thousand, five hundred eighty-nine".