261904840 has 32 divisors (see below), whose sum is σ = 596393280. Its totient is φ = 103498432.

The previous prime is 261904837. The next prime is 261904849. The reversal of 261904840 is 48409162.

It is a junction number, because it is equal to n+sod(n) for n = 261904796 and 261904805.

It is not an unprimeable number, because it can be changed into a prime (261904849) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36124 + ... + 42763.

It is an arithmetic number, because the mean of its divisors is an integer number (18637290).

Almost surely, 2^261904840 is an apocalyptic number.

261904840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261904840 is an abundant number, since it is smaller than the sum of its proper divisors (334488440).

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

261904840 is a wasteful number, since it uses less digits than its factorization.

261904840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78981 (or 78977 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 261904840 is about 16183.4742870621. The cubic root of 261904840 is about 639.8053118756.

The spelling of 261904840 in words is "two hundred sixty-one million, nine hundred four thousand, eight hundred forty".