261640418 has 16 divisors (see below), whose sum is σ = 425455296. Its totient is φ = 119955600.

The previous prime is 261640411. The next prime is 261640441. The reversal of 261640418 is 814046162.

It is not an unprimeable number, because it can be changed into a prime (261640411) by changing a digit.

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, 29396 + ... + 37247.

It is an arithmetic number, because the mean of its divisors is an integer number (26590956).

Almost surely, 2^261640418 is an apocalyptic number.

261640418 is a deficient number, since it is larger than the sum of its proper divisors (163814878).

261640418 is a wasteful number, since it uses less digits than its factorization.

261640418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66809.

The product of its (nonzero) digits is 9216, while the sum is 32.

The square root of 261640418 is about 16175.3027174146. The cubic root of 261640418 is about 639.5899212182.

It can be divided in two parts, 2616 and 40418, that added together give a palindrome (43034).

The spelling of 261640418 in words is "two hundred sixty-one million, six hundred forty thousand, four hundred eighteen".