2561649247 has 4 divisors (see below), whose sum is σ = 2561753376. Its totient is φ = 2561545120.

The previous prime is 2561649143. The next prime is 2561649253. The reversal of 2561649247 is 7429461652.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 2561649247 - 2⁷ = 2561649119 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2561649197 and 2561649206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561649287) 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, 7722 + ... + 71992.

It is an arithmetic number, because the mean of its divisors is an integer number (640438344).

Almost surely, 2^2561649247 is an apocalyptic number.

2561649247 is a deficient number, since it is larger than the sum of its proper divisors (104129).

2561649247 is an equidigital number, since it uses as much as digits as its factorization.

2561649247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104128.

The product of its digits is 725760, while the sum is 46.

The square root of 2561649247 is about 50612.7379915373. The cubic root of 2561649247 is about 1368.2744622681.

The spelling of 2561649247 in words is "two billion, five hundred sixty-one million, six hundred forty-nine thousand, two hundred forty-seven".