261686544 has 160 divisors (see below), whose sum is σ = 821376000. Its totient is φ = 70129152.

The previous prime is 261686527. The next prime is 261686549. The reversal of 261686544 is 445686162.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 261686496 and 261686505.

It is not an unprimeable number, because it can be changed into a prime (261686549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1142622 + ... + 1142850.

It is an arithmetic number, because the mean of its divisors is an integer number (5133600).

Almost surely, 2^261686544 is an apocalyptic number.

261686544 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 261686544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (410688000).

261686544 is an abundant number, since it is smaller than the sum of its proper divisors (559689456).

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

261686544 is a wasteful number, since it uses less digits than its factorization.

261686544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 445 (or 439 counting only the distinct ones).

The product of its digits is 276480, while the sum is 42.

The square root of 261686544 is about 16176.7284702439. The cubic root of 261686544 is about 639.6275045949.

The spelling of 261686544 in words is "two hundred sixty-one million, six hundred eighty-six thousand, five hundred forty-four".