991921103 has 2 divisors, whose sum is σ = 991921104. Its totient is φ = 991921102.

The previous prime is 991921093. The next prime is 991921111. The reversal of 991921103 is 301129199.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 991921103 - 2¹² = 991917007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991921193) 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, 495960551 + 495960552.

It is an arithmetic number, because the mean of its divisors is an integer number (495960552).

Almost surely, 2^991921103 is an apocalyptic number.

991921103 is a deficient number, since it is larger than the sum of its proper divisors (1).

991921103 is an equidigital number, since it uses as much as digits as its factorization.

991921103 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4374, while the sum is 35.

The square root of 991921103 is about 31494.7789800151. The cubic root of 991921103 is about 997.2997495436.

The spelling of 991921103 in words is "nine hundred ninety-one million, nine hundred twenty-one thousand, one hundred three".