261121560 has 128 divisors (see below), whose sum is σ = 942451200. Its totient is φ = 56540160.

The previous prime is 261121559. The next prime is 261121561. The reversal of 261121560 is 65121162.

It is an interprime number because it is at equal distance from previous prime (261121559) and next prime (261121561).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 261121560.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261121561) 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, 7780 + ... + 24140.

It is an arithmetic number, because the mean of its divisors is an integer number (7362900).

Almost surely, 2^261121560 is an apocalyptic number.

261121560 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 261121560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (471225600).

261121560 is an abundant number, since it is smaller than the sum of its proper divisors (681329640).

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

261121560 is a wasteful number, since it uses less digits than its factorization.

261121560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16401 (or 16397 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 261121560 is about 16159.2561710000. The cubic root of 261121560 is about 639.1668520819.

It can be divided in two parts, 26112 and 1560, that added together give a palindrome (27672).

The spelling of 261121560 in words is "two hundred sixty-one million, one hundred twenty-one thousand, five hundred sixty".