68821 has 2 divisors, whose sum is σ = 68822.
Its totient is φ = 68820.
The previous prime is 68819. The next prime is 68863. The reversal of 68821 is 12886.
68821 = 1852 + 1862.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 34596 + 34225 = 186^2 + 185^2
It is a cyclic number.
It is not a de Polignac number, because 68821 - 21 = 68819 is a prime.
Together with 68819, it forms a pair of twin primes.
It is an Ulam number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (68881) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 34410 + 34411.
It is an arithmetic number, because the mean of its divisors is an integer number (34411).
268821 is an apocalyptic number.
68821 is the 186-th centered square number.
It is an amenable number.
68821 is a deficient number, since it is larger than the sum of its proper divisors (1).
68821 is an equidigital number, since it uses as much as digits as its factorization.
68821 is an evil number, because the sum of its binary digits is even.
The product of its digits is 768, while the sum is 25.
The square root of 68821 is about 262.3375687926.
The cubic root of 68821 is about 40.9801609352.
The spelling of 68821 in words is "sixty-eight thousand, eight hundred twenty-one".