340821 has 16 divisors (see below), whose sum is σ = 544320. Its totient is φ = 209520.

The previous prime is 340819. The next prime is 340849. The reversal of 340821 is 128043.

It is a happy number.

It is not a de Polignac number, because 340821 - 2¹ = 340819 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 340794 and 340803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (340801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 135 + ... + 836.

It is an arithmetic number, because the mean of its divisors is an integer number (34020).

2³⁴⁰⁸²¹ is an apocalyptic number.

It is an amenable number.

340821 is a deficient number, since it is larger than the sum of its proper divisors (203499).

340821 is a wasteful number, since it uses less digits than its factorization.

340821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 993 (or 987 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 340821 is about 583.7987666996. The cubic root of 340821 is about 69.8514537019.

Adding to 340821 its reverse (128043), we get a palindrome (468864).

The spelling of 340821 in words is "three hundred forty thousand, eight hundred twenty-one".