2561771520 has 864 divisors, whose sum is σ = 11682740160. Its totient is φ = 504299520.

The previous prime is 2561771491. The next prime is 2561771543. The reversal of 2561771520 is 251771652.

2561771520 is a `hidden beast` number, since 2 + 5 + 61 + 7 + 71 + 520 = 666.

It is a super-2 number, since 2×2561771520² = 13125346641366220800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 134830071 + ... + 134830089.

It is an arithmetic number, because the mean of its divisors is an integer number (13521690).

Almost surely, 2^2561771520 is an apocalyptic number.

2561771520 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 2561771520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5841370080).

2561771520 is an abundant number, since it is smaller than the sum of its proper divisors (9120968640).

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

2561771520 is a wasteful number, since it uses less digits than its factorization.

2561771520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 47 counting only the distinct ones).

The product of its (nonzero) digits is 29400, while the sum is 36.

The square root of 2561771520 is about 50613.9459042663. The cubic root of 2561771520 is about 1368.2962321444.

The spelling of 2561771520 in words is "two billion, five hundred sixty-one million, seven hundred seventy-one thousand, five hundred twenty".