103821 has 4 divisors (see below), whose sum is σ = 138432. Its totient is φ = 69212.

The previous prime is 103813. The next prime is 103837. The reversal of 103821 is 128301.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 128301 = 3 ⋅42767.

It is a cyclic number.

It is not a de Polignac number, because 103821 - 2³ = 103813 is a prime.

It is a D-number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 103821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (103801) 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, 17301 + ... + 17306.

It is an arithmetic number, because the mean of its divisors is an integer number (34608).

2¹⁰³⁸²¹ is an apocalyptic number.

It is an amenable number.

103821 is a deficient number, since it is larger than the sum of its proper divisors (34611).

103821 is an equidigital number, since it uses as much as digits as its factorization.

103821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34610.

The product of its (nonzero) digits is 48, while the sum is 15.

The square root of 103821 is about 322.2126626934. The cubic root of 103821 is about 46.9996982024. Note that the first 3 decimals are identical.

The spelling of 103821 in words is "one hundred three thousand, eight hundred twenty-one".