1661539 has 4 divisors (see below), whose sum is σ = 1812600. Its totient is φ = 1510480.

The previous prime is 1661519. The next prime is 1661549. The reversal of 1661539 is 9351661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1661539 - 2¹¹ = 1659491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1661539.

It is not an unprimeable number, because it can be changed into a prime (1661519) 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 3 ways as a sum of consecutive naturals, for example, 75514 + ... + 75535.

It is an arithmetic number, because the mean of its divisors is an integer number (453150).

2^1661539 is an apocalyptic number.

1661539 is a deficient number, since it is larger than the sum of its proper divisors (151061).

1661539 is a wasteful number, since it uses less digits than its factorization.

1661539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151060.

The product of its digits is 4860, while the sum is 31.

The square root of 1661539 is about 1289.0069821378. The cubic root of 1661539 is about 118.4413948195.

The spelling of 1661539 in words is "one million, six hundred sixty-one thousand, five hundred thirty-nine".