261684864 has 256 divisors, whose sum is σ = 915552000. Its totient is φ = 71995392.

The previous prime is 261684847. The next prime is 261684887. The reversal of 261684864 is 468486162.

261684864 is a `hidden beast` number, since 2 + 6 + 168 + 486 + 4 = 666.

It is a nude number because it is divisible by every one of its digits.

Its product of digits (442368) is a multiple of the sum of its prime factors (432).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 701382 + ... + 701754.

It is an arithmetic number, because the mean of its divisors is an integer number (3576375).

Almost surely, 2^261684864 is an apocalyptic number.

261684864 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 261684864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (457776000).

261684864 is an abundant number, since it is smaller than the sum of its proper divisors (653867136).

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

261684864 is a wasteful number, since it uses less digits than its factorization.

261684864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 432 (or 414 counting only the distinct ones).

The product of its digits is 442368, while the sum is 45.

The square root of 261684864 is about 16176.6765437156. The cubic root of 261684864 is about 639.6261358116.

The spelling of 261684864 in words is "two hundred sixty-one million, six hundred eighty-four thousand, eight hundred sixty-four".