993821 has 2 divisors, whose sum is σ = 993822. Its totient is φ = 993820.

The previous prime is 993793. The next prime is 993823. The reversal of 993821 is 128399.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 912025 + 81796 = 955^2 + 286^2 .

It is an emirp because it is prime and its reverse (128399) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 993821 - 2¹⁴ = 977437 is a prime.

Together with 993823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 993821.

It is not a weakly prime, because it can be changed into another prime (993823) by changing a digit.

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

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 496910 + 496911.

It is an arithmetic number, because the mean of its divisors is an integer number (496911).

2⁹⁹³⁸²¹ is an apocalyptic number.

It is an amenable number.

993821 is a deficient number, since it is larger than the sum of its proper divisors (1).

993821 is an equidigital number, since it uses as much as digits as its factorization.

993821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 32.

The square root of 993821 is about 996.9057126930. The cubic root of 993821 is about 99.7936076484.

The spelling of 993821 in words is "nine hundred ninety-three thousand, eight hundred twenty-one".