1986691 has 4 divisors (see below), whose sum is σ = 2270512. Its totient is φ = 1702872.

The previous prime is 1986689. The next prime is 1986713. The reversal of 1986691 is 1966891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1966891 = 23 ⋅85517.

It is a cyclic number.

It is not a de Polignac number, because 1986691 - 2¹ = 1986689 is a prime.

It is a super-2 number, since 2×1986691² = 7893882258962, which contains 22 as substring.

It is the 1410-th Hogben number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1986601) by changing a digit.

It is a nontrivial repunit in base 1409.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141900 + ... + 141913.

It is an arithmetic number, because the mean of its divisors is an integer number (567628).

2^1986691 is an apocalyptic number.

1986691 is a deficient number, since it is larger than the sum of its proper divisors (283821).

1986691 is an equidigital number, since it uses as much as digits as its factorization.

1986691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283820.

The product of its digits is 23328, while the sum is 40.

The square root of 1986691 is about 1409.5002660518. The cubic root of 1986691 is about 125.7120112856.

It can be divided in two parts, 198 and 6691, that added together give a square (6889 = 83²).

The spelling of 1986691 in words is "one million, nine hundred eighty-six thousand, six hundred ninety-one".