33821 has 4 divisors (see below), whose sum is σ = 34944. Its totient is φ = 32700.

The previous prime is 33811. The next prime is 33827. The reversal of 33821 is 12833.

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: 12833 = 41 ⋅313.

It is a cyclic number.

It is not a de Polignac number, because 33821 - 2⁶ = 33757 is a prime.

It is a super-2 number, since 2×33821² = 2287720082, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 33821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (33827) 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, 515 + ... + 576.

It is an arithmetic number, because the mean of its divisors is an integer number (8736).

2³³⁸²¹ is an apocalyptic number.

33821 is a gapful number since it is divisible by the number (31) formed by its first and last digit.

It is an amenable number.

33821 is a deficient number, since it is larger than the sum of its proper divisors (1123).

33821 is a wasteful number, since it uses less digits than its factorization.

33821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1122.

The product of its digits is 144, while the sum is 17.

The square root of 33821 is about 183.9048667110. The cubic root of 33821 is about 32.3391659392.

The spelling of 33821 in words is "thirty-three thousand, eight hundred twenty-one".