991908393611 has 2 divisors, whose sum is σ = 991908393612. Its totient is φ = 991908393610.

The previous prime is 991908393569. The next prime is 991908393617. The reversal of 991908393611 is 116393809199.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991908393611 is a prime.

It is a super-2 number, since 2×991908393611² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (991908393617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495954196805 + 495954196806.

It is an arithmetic number, because the mean of its divisors is an integer number (495954196806).

Almost surely, 2^991908393611 is an apocalyptic number.

991908393611 is a deficient number, since it is larger than the sum of its proper divisors (1).

991908393611 is an equidigital number, since it uses as much as digits as its factorization.

991908393611 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2834352, while the sum is 59.

The spelling of 991908393611 in words is "nine hundred ninety-one billion, nine hundred eight million, three hundred ninety-three thousand, six hundred eleven".