1986440 has 32 divisors (see below), whose sum is σ = 4558680. Its totient is φ = 778752.

The previous prime is 1986437. The next prime is 1986443. The reversal of 1986440 is 446891.

It is an interprime number because it is at equal distance from previous prime (1986437) and next prime (1986443).

It can be written as a sum of positive squares in 4 ways, for example, as 1304164 + 682276 = 1142^2 + 826^2 .

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 1986397 and 1986406.

It is not an unprimeable number, because it can be changed into a prime (1986443) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1652 + ... + 2588.

2^1986440 is an apocalyptic number.

1986440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1986440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2279340).

1986440 is an abundant number, since it is smaller than the sum of its proper divisors (2572240).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1986440 is a wasteful number, since it uses less digits than its factorization.

1986440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001 (or 997 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 1986440 is about 1409.4112245899. The cubic root of 1986440 is about 125.7067168800.

The spelling of 1986440 in words is "one million, nine hundred eighty-six thousand, four hundred forty".