919991689 has 2 divisors, whose sum is σ = 919991690. Its totient is φ = 919991688.

The previous prime is 919991627. The next prime is 919991693. The reversal of 919991689 is 986199919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 541027600 + 378964089 = 23260^2 + 19467^2 .

It is a cyclic number.

It is not a de Polignac number, because 919991689 - 2⁷ = 919991561 is a prime.

It is not a weakly prime, because it can be changed into another prime (919991089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 459995844 + 459995845.

It is an arithmetic number, because the mean of its divisors is an integer number (459995845).

Almost surely, 2^919991689 is an apocalyptic number.

It is an amenable number.

919991689 is a deficient number, since it is larger than the sum of its proper divisors (1).

919991689 is an equidigital number, since it uses as much as digits as its factorization.

919991689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2834352, while the sum is 61.

The square root of 919991689 is about 30331.3647731189. The cubic root of 919991689 is about 972.5858975196.

The spelling of 919991689 in words is "nine hundred nineteen million, nine hundred ninety-one thousand, six hundred eighty-nine".