2561778 has 24 divisors (see below), whose sum is σ = 5730816. Its totient is φ = 826200.

The previous prime is 2561771. The next prime is 2561807. The reversal of 2561778 is 8771652.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (2561771) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1738 + ... + 2853.

It is an arithmetic number, because the mean of its divisors is an integer number (238784).

2^2561778 is an apocalyptic number.

2561778 is an abundant number, since it is smaller than the sum of its proper divisors (3169038).

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

2561778 is a wasteful number, since it uses less digits than its factorization.

2561778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4630 (or 4627 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 2561778 is about 1600.5555285588. Note that the first 4 decimals coincide. The cubic root of 2561778 is about 136.8297385845.

The spelling of 2561778 in words is "two million, five hundred sixty-one thousand, seven hundred seventy-eight".