2561304640 has 56 divisors (see below), whose sum is σ = 6108557760. Its totient is φ = 1022934528.

The previous prime is 2561304611. The next prime is 2561304667. The reversal of 2561304640 is 464031652.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 212701 + ... + 224419.

Almost surely, 2^2561304640 is an apocalyptic number.

2561304640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2561304640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3054278880).

2561304640 is an abundant number, since it is smaller than the sum of its proper divisors (3547253120).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2561304640 is a wasteful number, since it uses less digits than its factorization.

2561304640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12419 (or 12409 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 31.

The square root of 2561304640 is about 50609.3335265344. Note that the first 3 decimals coincide. The cubic root of 2561304640 is about 1368.2131036072.

The spelling of 2561304640 in words is "two billion, five hundred sixty-one million, three hundred four thousand, six hundred forty".