261155245560 has 256 divisors, whose sum is σ = 906110668800. Its totient is φ = 59611852800.

The previous prime is 261155245511. The next prime is 261155245627. The reversal of 261155245560 is 65542551162.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1427796 + ... + 1600284.

It is an arithmetic number, because the mean of its divisors is an integer number (3539494800).

Almost surely, 2^261155245560 is an apocalyptic number.

261155245560 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 261155245560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (453055334400).

261155245560 is an abundant number, since it is smaller than the sum of its proper divisors (644955423240).

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

261155245560 is a wasteful number, since it uses less digits than its factorization.

261155245560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172582 (or 172578 counting only the distinct ones).

The product of its (nonzero) digits is 360000, while the sum is 42.

The spelling of 261155245560 in words is "two hundred sixty-one billion, one hundred fifty-five million, two hundred forty-five thousand, five hundred sixty".