2561666550 has 48 divisors (see below), whose sum is σ = 6360188160. Its totient is φ = 682331040.

The previous prime is 2561666519. The next prime is 2561666567. The reversal of 2561666550 is 556661652.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 128559 + ... + 147141.

It is an arithmetic number, because the mean of its divisors is an integer number (132503920).

Almost surely, 2^2561666550 is an apocalyptic number.

2561666550 is an abundant number, since it is smaller than the sum of its proper divisors (3798521610).

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

2561666550 is a wasteful number, since it uses less digits than its factorization.

2561666550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19517 (or 19512 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 42.

The square root of 2561666550 is about 50612.9089264784. The cubic root of 2561666550 is about 1368.2775429917.

The spelling of 2561666550 in words is "two billion, five hundred sixty-one million, six hundred sixty-six thousand, five hundred fifty".