261538634448 has 720 divisors, whose sum is σ = 975278828160. Its totient is φ = 64705665024.

The previous prime is 261538634443. The next prime is 261538634473. The reversal of 261538634448 is 844436835162.

261538634448 is a `hidden beast` number, since 2 + 6 + 1 + 538 + 63 + 4 + 4 + 48 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 261538634394 and 261538634403.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261538634443) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 111815263 + ... + 111817601.

It is an arithmetic number, because the mean of its divisors is an integer number (1354553928).

Almost surely, 2^261538634448 is an apocalyptic number.

261538634448 is a gapful number since it is divisible by the number (28) 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 261538634448, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (487639414080).

261538634448 is an abundant number, since it is smaller than the sum of its proper divisors (713740193712).

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

261538634448 is a wasteful number, since it uses less digits than its factorization.

261538634448 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2456 (or 2440 counting only the distinct ones).

The product of its digits is 13271040, while the sum is 54.

The spelling of 261538634448 in words is "two hundred sixty-one billion, five hundred thirty-eight million, six hundred thirty-four thousand, four hundred forty-eight".