2561999880 has 128 divisors (see below), whose sum is σ = 8611505280. Its totient is φ = 604293120.

The previous prime is 2561999879. The next prime is 2561999887. The reversal of 2561999880 is 889991652.

It is a self number, because there is not a number n which added to its sum of digits gives 2561999880.

It is not an unprimeable number, because it can be changed into a prime (2561999887) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 22612 + ... + 75068.

It is an arithmetic number, because the mean of its divisors is an integer number (67277385).

Almost surely, 2^2561999880 is an apocalyptic number.

2561999880 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 2561999880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4305752640).

2561999880 is an abundant number, since it is smaller than the sum of its proper divisors (6049505400).

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

2561999880 is a wasteful number, since it uses less digits than its factorization.

2561999880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52519 (or 52515 counting only the distinct ones).

The product of its (nonzero) digits is 2799360, while the sum is 57.

The square root of 2561999880 is about 50616.2017539839. The cubic root of 2561999880 is about 1368.3368882348.

The spelling of 2561999880 in words is "two billion, five hundred sixty-one million, nine hundred ninety-nine thousand, eight hundred eighty".