991626983497 has 2 divisors, whose sum is σ = 991626983498. Its totient is φ = 991626983496.

The previous prime is 991626983447. The next prime is 991626983509. The reversal of 991626983497 is 794389626199.

991626983497 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 615528117136 + 376098866361 = 784556^2 + 613269^2 .

It is a cyclic number.

It is not a de Polignac number, because 991626983497 - 2¹⁹ = 991626459209 is a prime.

It is not a weakly prime, because it can be changed into another prime (991626983447) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495813491748 + 495813491749.

It is an arithmetic number, because the mean of its divisors is an integer number (495813491749).

Almost surely, 2^991626983497 is an apocalyptic number.

It is an amenable number.

991626983497 is a deficient number, since it is larger than the sum of its proper divisors (1).

991626983497 is an equidigital number, since it uses as much as digits as its factorization.

991626983497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 317447424, while the sum is 73.

The spelling of 991626983497 in words is "nine hundred ninety-one billion, six hundred twenty-six million, nine hundred eighty-three thousand, four hundred ninety-seven".