19991278313 has 2 divisors, whose sum is σ = 19991278314. Its totient is φ = 19991278312.

The previous prime is 19991278283. The next prime is 19991278327. The reversal of 19991278313 is 31387219991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18765438169 + 1225840144 = 136987^2 + 35012^2 .

It is a cyclic number.

It is not a de Polignac number, because 19991278313 - 2⁶ = 19991278249 is a prime.

It is not a weakly prime, because it can be changed into another prime (19991278213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9995639156 + 9995639157.

It is an arithmetic number, because the mean of its divisors is an integer number (9995639157).

Almost surely, 2^19991278313 is an apocalyptic number.

It is an amenable number.

19991278313 is a deficient number, since it is larger than the sum of its proper divisors (1).

19991278313 is an equidigital number, since it uses as much as digits as its factorization.

19991278313 is an evil number, because the sum of its binary digits is even.

The product of its digits is 734832, while the sum is 53.

The spelling of 19991278313 in words is "nineteen billion, nine hundred ninety-one million, two hundred seventy-eight thousand, three hundred thirteen".