1981385 has 8 divisors (see below), whose sum is σ = 2717376. Its totient is φ = 1358640.

The previous prime is 1981361. The next prime is 1981393. The reversal of 1981385 is 5831891.

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

It is not a de Polignac number, because 1981385 - 2¹⁰ = 1980361 is a prime.

It is a super-3 number, since 3×1981385³ = 23336077976739724875, which contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (35), and also a Moran number because the ratio is a prime number: 56611 = 1981385 / (1 + 9 + 8 + 1 + 3 + 8 + 5).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28271 + ... + 28340.

It is an arithmetic number, because the mean of its divisors is an integer number (339672).

2^1981385 is an apocalyptic number.

It is an amenable number.

1981385 is a deficient number, since it is larger than the sum of its proper divisors (735991).

1981385 is an equidigital number, since it uses as much as digits as its factorization.

1981385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56623.

The product of its digits is 8640, while the sum is 35.

The square root of 1981385 is about 1407.6167802353. The cubic root of 1981385 is about 125.5999954359.

The spelling of 1981385 in words is "one million, nine hundred eighty-one thousand, three hundred eighty-five".