261547438464 has 768 divisors, whose sum is σ = 891072000000. Its totient is φ = 72917729280.

The previous prime is 261547438459. The next prime is 261547438487. The reversal of 261547438464 is 464834745162.

261547438464 is a `hidden beast` number, since 2 + 6 + 1 + 547 + 4 + 38 + 4 + 64 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 261547438464.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1314308637 + ... + 1314308835.

It is an arithmetic number, because the mean of its divisors is an integer number (1160250000).

Almost surely, 2^261547438464 is an apocalyptic number.

261547438464 is a gapful number since it is divisible by the number (24) 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 261547438464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (445536000000).

261547438464 is an abundant number, since it is smaller than the sum of its proper divisors (629524561536).

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

261547438464 is a wasteful number, since it uses less digits than its factorization.

261547438464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431 (or 416 counting only the distinct ones).

The product of its digits is 15482880, while the sum is 54.

The spelling of 261547438464 in words is "two hundred sixty-one billion, five hundred forty-seven million, four hundred thirty-eight thousand, four hundred sixty-four".