2561641992 has 384 divisors, whose sum is σ = 8910720000. Its totient is φ = 660441600.

The previous prime is 2561641963. The next prime is 2561642009. The reversal of 2561641992 is 2991461652.

2561641992 is a `hidden beast` number, since 25 + 616 + 4 + 1 + 9 + 9 + 2 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 25362742 + ... + 25362842.

It is an arithmetic number, because the mean of its divisors is an integer number (23205000).

Almost surely, 2^2561641992 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2561641992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4455360000).

2561641992 is an abundant number, since it is smaller than the sum of its proper divisors (6349078008).

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

2561641992 is a wasteful number, since it uses less digits than its factorization.

2561641992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226 (or 205 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 2561641992 is about 50612.6663198058. Note that the first 3 decimals coincide. The cubic root of 2561641992 is about 1368.2731705429.

The spelling of 2561641992 in words is "two billion, five hundred sixty-one million, six hundred forty-one thousand, nine hundred ninety-two".