261560640 has 448 divisors, whose sum is σ = 1011253248. Its totient is φ = 56524800.

The previous prime is 261560627. The next prime is 261560647. The reversal of 261560640 is 46065162.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 261560598 and 261560607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261560647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5565097 + ... + 5565143.

Almost surely, 2^261560640 is an apocalyptic number.

261560640 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 261560640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (505626624).

261560640 is an abundant number, since it is smaller than the sum of its proper divisors (749692608).

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

261560640 is a wasteful number, since it uses less digits than its factorization.

261560640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 261560640 is about 16172.8364859106. The cubic root of 261560640 is about 639.5249078280.

The spelling of 261560640 in words is "two hundred sixty-one million, five hundred sixty thousand, six hundred forty".