1981659 has 8 divisors (see below), whose sum is σ = 2681920. Its totient is φ = 1301256.

The previous prime is 1981649. The next prime is 1981663. The reversal of 1981659 is 9561891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1981659 - 2⁵ = 1981627 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981619) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4729 + ... + 5130.

It is an arithmetic number, because the mean of its divisors is an integer number (335240).

2^1981659 is an apocalyptic number.

1981659 is a deficient number, since it is larger than the sum of its proper divisors (700261).

1981659 is an equidigital number, since it uses as much as digits as its factorization.

1981659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9929.

The product of its digits is 19440, while the sum is 39.

The square root of 1981659 is about 1407.7141044971. The cubic root of 1981659 is about 125.6057847891.

The spelling of 1981659 in words is "one million, nine hundred eighty-one thousand, six hundred fifty-nine".