9919781213 has 2 divisors, whose sum is σ = 9919781214. Its totient is φ = 9919781212.

The previous prime is 9919781167. The next prime is 9919781239. The reversal of 9919781213 is 3121879199.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9628123129 + 291658084 = 98123^2 + 17078^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9919781213 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9919781273) 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, 4959890606 + 4959890607.

It is an arithmetic number, because the mean of its divisors is an integer number (4959890607).

Almost surely, 2^9919781213 is an apocalyptic number.

It is an amenable number.

9919781213 is a deficient number, since it is larger than the sum of its proper divisors (1).

9919781213 is an equidigital number, since it uses as much as digits as its factorization.

9919781213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 50.

The square root of 9919781213 is about 99598.0984406831. The cubic root of 9919781213 is about 2148.6583454247.

The spelling of 9919781213 in words is "nine billion, nine hundred nineteen million, seven hundred eighty-one thousand, two hundred thirteen".