261138528 has 72 divisors (see below), whose sum is σ = 848706768. Its totient is φ = 74610432.

The previous prime is 261138523. The next prime is 261138539. The reversal of 261138528 is 825831162.

It is a happy number.

261138528 is a `hidden beast` number, since 2 + 611 + 38 + 5 + 2 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 261138492 and 261138501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261138523) 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 11 ways as a sum of consecutive naturals, for example, 62751 + ... + 66782.

It is an arithmetic number, because the mean of its divisors is an integer number (11787594).

Almost surely, 2^261138528 is an apocalyptic number.

261138528 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

261138528 is an abundant number, since it is smaller than the sum of its proper divisors (587568240).

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

261138528 is a wasteful number, since it uses less digits than its factorization.

261138528 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129556 (or 129545 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 261138528 is about 16159.7811866374. The cubic root of 261138528 is about 639.1806963980.

The spelling of 261138528 in words is "two hundred sixty-one million, one hundred thirty-eight thousand, five hundred twenty-eight".