2003657561 has 4 divisors (see below), whose sum is σ = 2008120500. Its totient is φ = 1999194624.

The previous prime is 2003657543. The next prime is 2003657563. The reversal of 2003657561 is 1657563002.

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

It can be written as a sum of positive squares in 2 ways, for example, as 405257161 + 1598400400 = 20131^2 + 39980^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2003657561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2003657563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2230796 + ... + 2231693.

It is an arithmetic number, because the mean of its divisors is an integer number (502030125).

Almost surely, 2^2003657561 is an apocalyptic number.

It is an amenable number.

2003657561 is a deficient number, since it is larger than the sum of its proper divisors (4462939).

2003657561 is an equidigital number, since it uses as much as digits as its factorization.

2003657561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4462938.

The product of its (nonzero) digits is 37800, while the sum is 35.

The square root of 2003657561 is about 44762.2336462335. The cubic root of 2003657561 is about 1260.6886218605.

The spelling of 2003657561 in words is "two billion, three million, six hundred fifty-seven thousand, five hundred sixty-one".