261688218 has 16 divisors (see below), whose sum is σ = 570956256. Its totient is φ = 79299440.

The previous prime is 261688177. The next prime is 261688279. The reversal of 261688218 is 812886162.

It is a self number, because there is not a number n which added to its sum of digits gives 261688218.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1982421 + ... + 1982552.

It is an arithmetic number, because the mean of its divisors is an integer number (35684766).

Almost surely, 2^261688218 is an apocalyptic number.

261688218 is an abundant number, since it is smaller than the sum of its proper divisors (309268038).

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

261688218 is a wasteful number, since it uses less digits than its factorization.

261688218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3964989.

The product of its digits is 73728, while the sum is 42.

The square root of 261688218 is about 16176.7802111545. The cubic root of 261688218 is about 639.6288684839.

The spelling of 261688218 in words is "two hundred sixty-one million, six hundred eighty-eight thousand, two hundred eighteen".