261313668 has 216 divisors, whose sum is σ = 872756640. Its totient is φ = 66860640.

The previous prime is 261313643. The next prime is 261313697. The reversal of 261313668 is 866313162.

261313668 is a `hidden beast` number, since 2 + 613 + 1 + 36 + 6 + 8 = 666.

It is a super-2 number, since 2×261313668² = 136569666167228448, which contains 22 as substring.

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

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 71 ways as a sum of consecutive naturals, for example, 3900171 + ... + 3900237.

It is an arithmetic number, because the mean of its divisors is an integer number (4040540).

Almost surely, 2^261313668 is an apocalyptic number.

261313668 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 261313668, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (436378320).

261313668 is an abundant number, since it is smaller than the sum of its proper divisors (611442972).

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

261313668 is a wasteful number, since it uses less digits than its factorization.

261313668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172 (or 90 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 261313668 is about 16165.1992873580. The cubic root of 261313668 is about 639.3235593843.

The spelling of 261313668 in words is "two hundred sixty-one million, three hundred thirteen thousand, six hundred sixty-eight".