1991684 has 12 divisors (see below), whose sum is σ = 3502044. Its totient is φ = 991104.

The previous prime is 1991681. The next prime is 1991707. The reversal of 1991684 is 4861991.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 222784 + 1768900 = 472^2 + 1330^2 .

It is not an unprimeable number, because it can be changed into a prime (1991681) 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, 137 + ... + 2000.

It is an arithmetic number, because the mean of its divisors is an integer number (291837).

2^1991684 is an apocalyptic number.

It is an amenable number.

1991684 is a deficient number, since it is larger than the sum of its proper divisors (1510360).

1991684 is a wasteful number, since it uses less digits than its factorization.

1991684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2374 (or 2372 counting only the distinct ones).

The product of its digits is 15552, while the sum is 38.

The square root of 1991684 is about 1411.2703497204. The cubic root of 1991684 is about 125.8172373410.

The spelling of 1991684 in words is "one million, nine hundred ninety-one thousand, six hundred eighty-four".