1691905387 has 4 divisors (see below), whose sum is σ = 1695269520. Its totient is φ = 1688541256.

The previous prime is 1691905381. The next prime is 1691905393. The reversal of 1691905387 is 7835091961.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7835091961 = 113 ⋅69337097.

It is an interprime number because it is at equal distance from previous prime (1691905381) and next prime (1691905393).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1691905387 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 1691905387.

It is not an unprimeable number, because it can be changed into a prime (1691905381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1681312 + ... + 1682317.

It is an arithmetic number, because the mean of its divisors is an integer number (423817380).

Almost surely, 2^1691905387 is an apocalyptic number.

1691905387 is a deficient number, since it is larger than the sum of its proper divisors (3364133).

1691905387 is an equidigital number, since it uses as much as digits as its factorization.

1691905387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3364132.

The product of its (nonzero) digits is 408240, while the sum is 49.

The square root of 1691905387 is about 41132.7775259585. Note that the first 3 decimals coincide. The cubic root of 1691905387 is about 1191.5859059183.

The spelling of 1691905387 in words is "one billion, six hundred ninety-one million, nine hundred five thousand, three hundred eighty-seven".