991026899 has 2 divisors, whose sum is σ = 991026900. Its totient is φ = 991026898.

The previous prime is 991026887. The next prime is 991026979. The reversal of 991026899 is 998620199.

It is a weak prime.

It is an emirp because it is prime and its reverse (998620199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991026899 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991026899.

It is not a weakly prime, because it can be changed into another prime (991026809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495513449 + 495513450.

It is an arithmetic number, because the mean of its divisors is an integer number (495513450).

Almost surely, 2^991026899 is an apocalyptic number.

991026899 is a deficient number, since it is larger than the sum of its proper divisors (1).

991026899 is an equidigital number, since it uses as much as digits as its factorization.

991026899 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 629856, while the sum is 53.

The square root of 991026899 is about 31480.5797119430. The cubic root of 991026899 is about 996.9999751847. Note that the first 4 decimals are identical.

The spelling of 991026899 in words is "nine hundred ninety-one million, twenty-six thousand, eight hundred ninety-nine".