261903261763440 has 720 divisors, whose sum is σ = 1000339619479200. Its totient is φ = 61289170145280.

The previous prime is 261903261763369. The next prime is 261903261763459. The reversal of 261903261763440 is 44367162309162.

261903261763440 is a `hidden beast` number, since 2 + 6 + 1 + 9 + 0 + 3 + 26 + 176 + 3 + 440 = 666.

It is a tau number, because it is divible by the number of its divisors (720).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 16768239951 + ... + 16768255569.

It is an arithmetic number, because the mean of its divisors is an integer number (1389360582610).

Almost surely, 2^{261903261763440} is an apocalyptic number.

261903261763440 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 261903261763440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (500169809739600).

261903261763440 is an abundant number, since it is smaller than the sum of its proper divisors (738436357715760).

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

261903261763440 is a wasteful number, since it uses less digits than its factorization.

261903261763440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22326 (or 22306 counting only the distinct ones).

The product of its (nonzero) digits is 7838208, while the sum is 54.

The spelling of 261903261763440 in words is "two hundred sixty-one trillion, nine hundred three billion, two hundred sixty-one million, seven hundred sixty-three thousand, four hundred forty".