1981705 has 16 divisors (see below), whose sum is σ = 2623104. Its totient is φ = 1425280.

The previous prime is 1981699. The next prime is 1981711. The reversal of 1981705 is 5071891.

It is an interprime number because it is at equal distance from previous prime (1981699) and next prime (1981711).

It is not a de Polignac number, because 1981705 - 2¹⁵ = 1948937 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7404 + ... + 7666.

It is an arithmetic number, because the mean of its divisors is an integer number (163944).

2^1981705 is an apocalyptic number.

It is an amenable number.

1981705 is a deficient number, since it is larger than the sum of its proper divisors (641399).

1981705 is a wasteful number, since it uses less digits than its factorization.

1981705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 416.

The product of its (nonzero) digits is 2520, while the sum is 31.

The square root of 1981705 is about 1407.7304429471. The cubic root of 1981705 is about 125.6067566720.

The spelling of 1981705 in words is "one million, nine hundred eighty-one thousand, seven hundred five".