961721221 has 2 divisors, whose sum is σ = 961721222. Its totient is φ = 961721220.

The previous prime is 961721207. The next prime is 961721227. The reversal of 961721221 is 122127169.

961721221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 702833121 + 258888100 = 26511^2 + 16090^2 .

It is a cyclic number.

It is not a de Polignac number, because 961721221 - 2¹¹ = 961719173 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (961721227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 480860610 + 480860611.

It is an arithmetic number, because the mean of its divisors is an integer number (480860611).

Almost surely, 2^961721221 is an apocalyptic number.

It is an amenable number.

961721221 is a deficient number, since it is larger than the sum of its proper divisors (1).

961721221 is an equidigital number, since it uses as much as digits as its factorization.

961721221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 31.

The square root of 961721221 is about 31011.6304150556. The cubic root of 961721221 is about 987.0740466198.

The spelling of 961721221 in words is "nine hundred sixty-one million, seven hundred twenty-one thousand, two hundred twenty-one".