1684861989 has 4 divisors (see below), whose sum is σ = 2246482656. Its totient is φ = 1123241324.

The previous prime is 1684861963. The next prime is 1684862009. The reversal of 1684861989 is 9891684861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9891684861 = 3 ⋅3297228287.

It is a cyclic number.

It is not a de Polignac number, because 1684861989 - 2¹⁵ = 1684829221 is a prime.

It is a super-2 number, since 2×1684861989² = 5677519843954072242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1684861589) 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, 280810329 + ... + 280810334.

It is an arithmetic number, because the mean of its divisors is an integer number (561620664).

Almost surely, 2^1684861989 is an apocalyptic number.

It is an amenable number.

1684861989 is a deficient number, since it is larger than the sum of its proper divisors (561620667).

1684861989 is an equidigital number, since it uses as much as digits as its factorization.

1684861989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 561620666.

The product of its digits is 5971968, while the sum is 60.

The square root of 1684861989 is about 41047.0704070339. The cubic root of 1684861989 is about 1189.9300829859.

The spelling of 1684861989 in words is "one billion, six hundred eighty-four million, eight hundred sixty-one thousand, nine hundred eighty-nine".