2561853966 has 64 divisors (see below), whose sum is σ = 6073420800. Its totient is φ = 719923680.

The previous prime is 2561853953. The next prime is 2561853967. The reversal of 2561853966 is 6693581652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2561853967) 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, 115335 + ... + 135741.

It is an arithmetic number, because the mean of its divisors is an integer number (94897200).

Almost surely, 2^2561853966 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2561853966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3036710400).

2561853966 is an abundant number, since it is smaller than the sum of its proper divisors (3511566834).

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

2561853966 is a wasteful number, since it uses less digits than its factorization.

2561853966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20494 (or 20480 counting only the distinct ones).

The product of its digits is 2332800, while the sum is 51.

The square root of 2561853966 is about 50614.7603570342. The cubic root of 2561853966 is about 1368.3109107031.

The spelling of 2561853966 in words is "two billion, five hundred sixty-one million, eight hundred fifty-three thousand, nine hundred sixty-six".