10217821 has 2 divisors, whose sum is σ = 10217822. Its totient is φ = 10217820.

The previous prime is 10217803. The next prime is 10217827. The reversal of 10217821 is 12871201.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10048900 + 168921 = 3170^2 + 411^2 .

It is a cyclic number.

It is not a de Polignac number, because 10217821 - 2¹⁵ = 10185053 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 10217792 and 10217801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (10217827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5108910 + 5108911.

It is an arithmetic number, because the mean of its divisors is an integer number (5108911).

Almost surely, 2^10217821 is an apocalyptic number.

It is an amenable number.

10217821 is a deficient number, since it is larger than the sum of its proper divisors (1).

10217821 is an equidigital number, since it uses as much as digits as its factorization.

10217821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 10217821 is about 3196.5326527348. The cubic root of 10217821 is about 216.9965171774.

The spelling of 10217821 in words is "ten million, two hundred seventeen thousand, eight hundred twenty-one".