1986381 has 6 divisors (see below), whose sum is σ = 2869230. Its totient is φ = 1324248.

The previous prime is 1986373. The next prime is 1986401. The reversal of 1986381 is 1836891.

1986381 is a `hidden beast` number, since 19 + 8 + 638 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1121481 + 864900 = 1059^2 + 930^2 .

It is not a de Polignac number, because 1986381 - 2³ = 1986373 is a prime.

It is a super-2 number, since 2×1986381² = 7891418954322, which contains 22 as substring.

1986381 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1986301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 110346 + ... + 110363.

It is an arithmetic number, because the mean of its divisors is an integer number (478205).

2^1986381 is an apocalyptic number.

It is an amenable number.

1986381 is a deficient number, since it is larger than the sum of its proper divisors (882849).

1986381 is a wasteful number, since it uses less digits than its factorization.

1986381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 220715 (or 220712 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 1986381 is about 1409.3902937086. The cubic root of 1986381 is about 125.7054723136.

The spelling of 1986381 in words is "one million, nine hundred eighty-six thousand, three hundred eighty-one".