2561397984 has 48 divisors (see below), whose sum is σ = 7470746640. Its totient is φ = 853799040.

The previous prime is 2561397977. The next prime is 2561397989. The reversal of 2561397984 is 4897931652.

2561397984 is a `hidden beast` number, since 2 + 561 + 3 + 9 + 79 + 8 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 2561397984.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561397989) 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, 1481427 + ... + 1483154.

It is an arithmetic number, because the mean of its divisors is an integer number (155640555).

Almost surely, 2^2561397984 is an apocalyptic number.

2561397984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

2561397984 is an abundant number, since it is smaller than the sum of its proper divisors (4909348656).

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

2561397984 is a wasteful number, since it uses less digits than its factorization.

2561397984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2964600 (or 2964586 counting only the distinct ones).

The product of its digits is 3265920, while the sum is 54.

The square root of 2561397984 is about 50610.2557195674. The cubic root of 2561397984 is about 1368.2297244249.

The spelling of 2561397984 in words is "two billion, five hundred sixty-one million, three hundred ninety-seven thousand, nine hundred eighty-four".