261728388 has 24 divisors (see below), whose sum is σ = 678555360. Its totient is φ = 87242760.

The previous prime is 261728371. The next prime is 261728419. The reversal of 261728388 is 883827162.

261728388 is a `hidden beast` number, since 2 + 617 + 28 + 3 + 8 + 8 = 666.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1211598 + ... + 1211813.

It is an arithmetic number, because the mean of its divisors is an integer number (28273140).

Almost surely, 2^261728388 is an apocalyptic number.

It is an amenable number.

261728388 is an abundant number, since it is smaller than the sum of its proper divisors (416826972).

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

261728388 is a wasteful number, since it uses less digits than its factorization.

261728388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2423424 (or 2423416 counting only the distinct ones).

The product of its digits is 258048, while the sum is 45.

The square root of 261728388 is about 16178.0217579283. The cubic root of 261728388 is about 639.6615951860.

The spelling of 261728388 in words is "two hundred sixty-one million, seven hundred twenty-eight thousand, three hundred eighty-eight".