9791221861 has 2 divisors, whose sum is σ = 9791221862. Its totient is φ = 9791221860.

The previous prime is 9791221837. The next prime is 9791222027. The reversal of 9791221861 is 1681221979.

9791221861 is digitally balanced in base 3, 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., 9137448100 + 653773761 = 95590^2 + 25569^2 .

It is an emirp because it is prime and its reverse (1681221979) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9791221861 - 2¹³ = 9791213669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9791261861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4895610930 + 4895610931.

It is an arithmetic number, because the mean of its divisors is an integer number (4895610931).

Almost surely, 2^9791221861 is an apocalyptic number.

It is an amenable number.

9791221861 is a deficient number, since it is larger than the sum of its proper divisors (1).

9791221861 is an equidigital number, since it uses as much as digits as its factorization.

9791221861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 46.

The square root of 9791221861 is about 98950.6031361103. The cubic root of 9791221861 is about 2139.3358247625.

The spelling of 9791221861 in words is "nine billion, seven hundred ninety-one million, two hundred twenty-one thousand, eight hundred sixty-one".