981821 has 4 divisors (see below), whose sum is σ = 991644. Its totient is φ = 972000.

The previous prime is 981817. The next prime is 981823. The reversal of 981821 is 128189.

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 470596 + 511225 = 686^2 + 715^2 .

It is a cyclic number.

It is not a de Polignac number, because 981821 - 2² = 981817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (981823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4760 + ... + 4961.

It is an arithmetic number, because the mean of its divisors is an integer number (247911).

2⁹⁸¹⁸²¹ is an apocalyptic number.

It is an amenable number.

981821 is a deficient number, since it is larger than the sum of its proper divisors (9823).

981821 is a wasteful number, since it uses less digits than its factorization.

981821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9822.

The product of its digits is 1152, while the sum is 29.

The square root of 981821 is about 990.8688106909. The cubic root of 981821 is about 99.3903238371.

The spelling of 981821 in words is "nine hundred eighty-one thousand, eight hundred twenty-one".