208821 has 8 divisors (see below), whose sum is σ = 284544. Its totient is φ = 136160.

The previous prime is 208807. The next prime is 208837. The reversal of 208821 is 128802.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 208821 - 2⁹ = 208309 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (208891) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 600 + ... + 881.

It is an arithmetic number, because the mean of its divisors is an integer number (35568).

2²⁰⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

208821 is a deficient number, since it is larger than the sum of its proper divisors (75723).

208821 is a wasteful number, since it uses less digits than its factorization.

208821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1531.

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 208821 is about 456.9693643998. The cubic root of 208821 is about 59.3277744515.

Multiplying 208821 by its sum of digits (21), we get a triangular number (4385241 = T₂₉₆₁).

The spelling of 208821 in words is "two hundred eight thousand, eight hundred twenty-one".