2645561813 has 4 divisors (see below), whose sum is σ = 2646517260. Its totient is φ = 2644606368.

The previous prime is 2645561797. The next prime is 2645561851. The reversal of 2645561813 is 3181655462.

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 1409476849 + 1236084964 = 37543^2 + 35158^2 .

It is a cyclic number.

It is not a de Polignac number, because 2645561813 - 2⁴ = 2645561797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2645561213) 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, 473558 + ... + 479111.

It is an arithmetic number, because the mean of its divisors is an integer number (661629315).

Almost surely, 2^2645561813 is an apocalyptic number.

It is an amenable number.

2645561813 is a deficient number, since it is larger than the sum of its proper divisors (955447).

2645561813 is an equidigital number, since it uses as much as digits as its factorization.

2645561813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 955446.

The product of its digits is 172800, while the sum is 41.

The square root of 2645561813 is about 51435.0251579602. The cubic root of 2645561813 is about 1383.0545329396.

The spelling of 2645561813 in words is "two billion, six hundred forty-five million, five hundred sixty-one thousand, eight hundred thirteen".