991649505919 has 2 divisors, whose sum is σ = 991649505920. Its totient is φ = 991649505918.

The previous prime is 991649505851. The next prime is 991649505923. The reversal of 991649505919 is 919505946199.

It is a strong prime.

It is an emirp because it is prime and its reverse (919505946199) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 991649505919 - 2³³ = 983059571327 is a prime.

It is a super-2 number, since 2×991649505919² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991649505949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495824752959 + 495824752960.

It is an arithmetic number, because the mean of its divisors is an integer number (495824752960).

Almost surely, 2^991649505919 is an apocalyptic number.

991649505919 is a deficient number, since it is larger than the sum of its proper divisors (1).

991649505919 is an equidigital number, since it uses as much as digits as its factorization.

991649505919 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 35429400, while the sum is 67.

The spelling of 991649505919 in words is "nine hundred ninety-one billion, six hundred forty-nine million, five hundred five thousand, nine hundred nineteen".