1983561 has 4 divisors (see below), whose sum is σ = 2644752. Its totient is φ = 1322372.

The previous prime is 1983559. The next prime is 1983563. The reversal of 1983561 is 1653891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1653891 = 3 ⋅551297.

It is an interprime number because it is at equal distance from previous prime (1983559) and next prime (1983563).

It is a cyclic number.

It is not a de Polignac number, because 1983561 - 2¹ = 1983559 is a prime.

It is a D-number.

It is a Curzon number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (1983563) 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, 330591 + ... + 330596.

It is an arithmetic number, because the mean of its divisors is an integer number (661188).

2^1983561 is an apocalyptic number.

It is an amenable number.

1983561 is a deficient number, since it is larger than the sum of its proper divisors (661191).

1983561 is an equidigital number, since it uses as much as digits as its factorization.

1983561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661190.

The product of its digits is 6480, while the sum is 33.

The square root of 1983561 is about 1408.3895057831. The cubic root of 1983561 is about 125.6459574946.

It can be divided in two parts, 198 and 3561, that multiplied together give a triangular number (705078 = T₁₁₈₇).

The spelling of 1983561 in words is "one million, nine hundred eighty-three thousand, five hundred sixty-one".