1691068891 has 2 divisors, whose sum is σ = 1691068892. Its totient is φ = 1691068890.

The previous prime is 1691068889. The next prime is 1691068937. The reversal of 1691068891 is 1988601961.

It is a happy number.

It is a weak prime.

It is an emirp because it is prime and its reverse (1988601961) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1688901691 and 1961098861.

It is a cyclic number.

It is not a de Polignac number, because 1691068891 - 2¹ = 1691068889 is a prime.

Together with 1691068889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1691068801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845534445 + 845534446.

It is an arithmetic number, because the mean of its divisors is an integer number (845534446).

Almost surely, 2^1691068891 is an apocalyptic number.

1691068891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1691068891 is an equidigital number, since it uses as much as digits as its factorization.

1691068891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 186624, while the sum is 49.

The square root of 1691068891 is about 41122.6080277017. The cubic root of 1691068891 is about 1191.3894959682.

The spelling of 1691068891 in words is "one billion, six hundred ninety-one million, sixty-eight thousand, eight hundred ninety-one".