1691918189 has 4 divisors (see below), whose sum is σ = 1822065756. Its totient is φ = 1561770624.

The previous prime is 1691918167. The next prime is 1691918197. The reversal of 1691918189 is 9818191961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9818191961 = 8231 ⋅1192831.

It can be written as a sum of positive squares in 2 ways, for example, as 804176164 + 887742025 = 28358^2 + 29795^2 .

It is a cyclic number.

It is not a de Polignac number, because 1691918189 - 2⁸ = 1691917933 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1691918189.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1691917189) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65073764 + ... + 65073789.

It is an arithmetic number, because the mean of its divisors is an integer number (455516439).

Almost surely, 2^1691918189 is an apocalyptic number.

It is an amenable number.

1691918189 is a deficient number, since it is larger than the sum of its proper divisors (130147567).

1691918189 is a wasteful number, since it uses less digits than its factorization.

1691918189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130147566.

The product of its digits is 279936, while the sum is 53.

The square root of 1691918189 is about 41132.9331436502. The cubic root of 1691918189 is about 1191.5889113355.

The spelling of 1691918189 in words is "one billion, six hundred ninety-one million, nine hundred eighteen thousand, one hundred eighty-nine".