9780987221 has 2 divisors, whose sum is σ = 9780987222. Its totient is φ = 9780987220.

The previous prime is 9780987211. The next prime is 9780987239. The reversal of 9780987221 is 1227890879.

It is a happy number.

9780987221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8182107025 + 1598880196 = 90455^2 + 39986^2 .

It is a cyclic number.

It is not a de Polignac number, because 9780987221 - 2¹⁰ = 9780986197 is a prime.

It is a super-2 number, since 2×9780987221² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9780987211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4890493610 + 4890493611.

It is an arithmetic number, because the mean of its divisors is an integer number (4890493611).

Almost surely, 2^9780987221 is an apocalyptic number.

It is an amenable number.

9780987221 is a deficient number, since it is larger than the sum of its proper divisors (1).

9780987221 is an equidigital number, since it uses as much as digits as its factorization.

9780987221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1016064, while the sum is 53.

The square root of 9780987221 is about 98898.8737094614. The cubic root of 9780987221 is about 2138.5901580241.

The spelling of 9780987221 in words is "nine billion, seven hundred eighty million, nine hundred eighty-seven thousand, two hundred twenty-one".