2561305563 has 8 divisors (see below), whose sum is σ = 3794526800. Its totient is φ = 1707537024.

The previous prime is 2561305517. The next prime is 2561305567. The reversal of 2561305563 is 3655031652.

2561305563 is a `hidden beast` number, since 2 + 5 + 61 + 30 + 5 + 563 = 666.

It is not a de Polignac number, because 2561305563 - 2¹² = 2561301467 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2561305567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47431558 + ... + 47431611.

It is an arithmetic number, because the mean of its divisors is an integer number (474315850).

Almost surely, 2^2561305563 is an apocalyptic number.

2561305563 is a deficient number, since it is larger than the sum of its proper divisors (1233221237).

2561305563 is an equidigital number, since it uses as much as digits as its factorization.

2561305563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94863178 (or 94863172 counting only the distinct ones).

The product of its (nonzero) digits is 81000, while the sum is 36.

The square root of 2561305563 is about 50609.3426454049. The cubic root of 2561305563 is about 1368.2132679584.

The spelling of 2561305563 in words is "two billion, five hundred sixty-one million, three hundred five thousand, five hundred sixty-three".