1800561 has 16 divisors (see below), whose sum is σ = 2764800. Its totient is φ = 1021008.

The previous prime is 1800553. The next prime is 1800563. The reversal of 1800561 is 1650081.

It is not a de Polignac number, because 1800561 - 2³ = 1800553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1800563) 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 15 ways as a sum of consecutive naturals, for example, 3520 + ... + 3998.

It is an arithmetic number, because the mean of its divisors is an integer number (172800).

2^1800561 is an apocalyptic number.

It is an amenable number.

1800561 is a deficient number, since it is larger than the sum of its proper divisors (964239).

1800561 is a wasteful number, since it uses less digits than its factorization.

1800561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 668.

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 1800561 is about 1341.8498425681. The cubic root of 1800561 is about 121.6566760629.

The spelling of 1800561 in words is "one million, eight hundred thousand, five hundred sixty-one".