2561621760 has 360 divisors, whose sum is σ = 9473498496. Its totient is φ = 660234240.

The previous prime is 2561621759. The next prime is 2561621767. The reversal of 2561621760 is 671261652.

It is a happy number.

2561621760 is a `hidden beast` number, since 2 + 561 + 6 + 21 + 76 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (360).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561621767) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3213682 + ... + 3214478.

Almost surely, 2^2561621760 is an apocalyptic number.

2561621760 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 2561621760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4736749248).

2561621760 is an abundant number, since it is smaller than the sum of its proper divisors (6911876736).

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

2561621760 is an equidigital number, since it uses as much as digits as its factorization.

2561621760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 861 (or 838 counting only the distinct ones).

The product of its (nonzero) digits is 30240, while the sum is 36.

The square root of 2561621760 is about 50612.4664484947. The cubic root of 2561621760 is about 1368.2695682993.

The spelling of 2561621760 in words is "two billion, five hundred sixty-one million, six hundred twenty-one thousand, seven hundred sixty".