1861605 has 24 divisors (see below), whose sum is σ = 3308760. Its totient is φ = 967680.

The previous prime is 1861591. The next prime is 1861621. The reversal of 1861605 is 5061681.

It can be written as a sum of positive squares in 4 ways, for example, as 6561 + 1855044 = 81^2 + 1362^2 .

It is not a de Polignac number, because 1861605 - 2⁴ = 1861589 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 1341 + ... + 2349.

It is an arithmetic number, because the mean of its divisors is an integer number (137865).

2^1861605 is an apocalyptic number.

1861605 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1861605 is a deficient number, since it is larger than the sum of its proper divisors (1447155).

1861605 is a wasteful number, since it uses less digits than its factorization.

1861605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1061 (or 1058 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 1861605 is about 1364.4064643646. The cubic root of 1861605 is about 123.0162580135.

The spelling of 1861605 in words is "one million, eight hundred sixty-one thousand, six hundred five".