908821 has 2 divisors, whose sum is σ = 908822. Its totient is φ = 908820.

The previous prime is 908819. The next prime is 908849. The reversal of 908821 is 128809.

It is an a-pointer prime, because the next prime (908849) can be obtained adding 908821 to its sum of digits (28).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 874225 + 34596 = 935^2 + 186^2 .

It is a cyclic number.

It is not a de Polignac number, because 908821 - 2¹ = 908819 is a prime.

It is a super-2 number, since 2×908821² = 1651911220082, which contains 22 as substring.

Together with 908819, it forms a pair of twin primes.

It is a Chen prime.

908821 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 908821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (908851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 454410 + 454411.

It is an arithmetic number, because the mean of its divisors is an integer number (454411).

2⁹⁰⁸⁸²¹ is an apocalyptic number.

It is an amenable number.

908821 is a deficient number, since it is larger than the sum of its proper divisors (1).

908821 is an equidigital number, since it uses as much as digits as its factorization.

908821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 908821 is about 953.3210372167. The cubic root of 908821 is about 96.8633424751.

It can be divided in two parts, 90 and 8821, that added together give a triangular number (8911 = T₁₃₃).

The spelling of 908821 in words is "nine hundred eight thousand, eight hundred twenty-one".