2178610561 has 4 divisors (see below), whose sum is σ = 2181719124. Its totient is φ = 2175502000.

The previous prime is 2178610559. The next prime is 2178610597. The reversal of 2178610561 is 1650168712.

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 1025600625 + 1153009936 = 32025^2 + 33956^2 .

It is a cyclic number.

It is not a de Polignac number, because 2178610561 - 2¹ = 2178610559 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 2178610561.

It is not an unprimeable number, because it can be changed into a prime (2178610261) 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, 1553230 + ... + 1554631.

It is an arithmetic number, because the mean of its divisors is an integer number (545429781).

Almost surely, 2^2178610561 is an apocalyptic number.

It is an amenable number.

2178610561 is a deficient number, since it is larger than the sum of its proper divisors (3108563).

2178610561 is an equidigital number, since it uses as much as digits as its factorization.

2178610561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3108562.

The product of its (nonzero) digits is 20160, while the sum is 37.

The square root of 2178610561 is about 46675.5884912017. The cubic root of 2178610561 is about 1296.3627244584.

The spelling of 2178610561 in words is "two billion, one hundred seventy-eight million, six hundred ten thousand, five hundred sixty-one".