981781 has 4 divisors (see below), whose sum is σ = 984652. Its totient is φ = 978912.

The previous prime is 981769. The next prime is 981797. The reversal of 981781 is 187189.

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

It can be written as a sum of positive squares in 2 ways, for example, as 695556 + 286225 = 834^2 + 535^2 .

It is a cyclic number.

It is not a de Polignac number, because 981781 - 2⁷ = 981653 is a prime.

It is a super-2 number, since 2×981781² = 1927787863922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981731) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 840 + ... + 1633.

It is an arithmetic number, because the mean of its divisors is an integer number (246163).

2⁹⁸¹⁷⁸¹ is an apocalyptic number.

It is an amenable number.

981781 is a deficient number, since it is larger than the sum of its proper divisors (2871).

981781 is a wasteful number, since it uses less digits than its factorization.

981781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2870.

The product of its digits is 4032, while the sum is 34.

The square root of 981781 is about 990.8486261786. The cubic root of 981781 is about 99.3889740775.

The spelling of 981781 in words is "nine hundred eighty-one thousand, seven hundred eighty-one".