261012640 has 96 divisors (see below), whose sum is σ = 708390144. Its totient is φ = 89026560.

The previous prime is 261012613. The next prime is 261012643. The reversal of 261012640 is 46210162.

It is not an unprimeable number, because it can be changed into a prime (261012643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 269437 + ... + 270403.

It is an arithmetic number, because the mean of its divisors is an integer number (7379064).

Almost surely, 2^261012640 is an apocalyptic number.

261012640 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 261012640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (354195072).

261012640 is an abundant number, since it is smaller than the sum of its proper divisors (447377504).

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

261012640 is a wasteful number, since it uses less digits than its factorization.

261012640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1230 (or 1222 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 261012640 is about 16155.8856148464. The cubic root of 261012640 is about 639.0779691678.

The spelling of 261012640 in words is "two hundred sixty-one million, twelve thousand, six hundred forty".