9919937221261 has 2 divisors, whose sum is σ = 9919937221262. Its totient is φ = 9919937221260.

The previous prime is 9919937221253. The next prime is 9919937221289. The reversal of 9919937221261 is 1621227399199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 6932636340100 + 2987300881161 = 2632990^2 + 1728381^2 .

It is an emirp because it is prime and its reverse (1621227399199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9919937221261 - 2³ = 9919937221253 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 9919937221261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9919937221241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4959968610630 + 4959968610631.

It is an arithmetic number, because the mean of its divisors is an integer number (4959968610631).

Almost surely, 2^{9919937221261} is an apocalyptic number.

It is an amenable number.

9919937221261 is a deficient number, since it is larger than the sum of its proper divisors (1).

9919937221261 is an equidigital number, since it uses as much as digits as its factorization.

9919937221261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6613488, while the sum is 61.

The spelling of 9919937221261 in words is "nine trillion, nine hundred nineteen billion, nine hundred thirty-seven million, two hundred twenty-one thousand, two hundred sixty-one".