261640578 has 8 divisors (see below), whose sum is σ = 523281168. Its totient is φ = 87213524.

The previous prime is 261640567. The next prime is 261640597. The reversal of 261640578 is 875046162.

It is a sphenic number, since it is the product of 3 distinct primes.

261640578 is an admirable number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21803376 + ... + 21803387.

It is an arithmetic number, because the mean of its divisors is an integer number (65410146).

Almost surely, 2^261640578 is an apocalyptic number.

261640578 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

261640578 is a wasteful number, since it uses less digits than its factorization.

261640578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43606768.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 261640578 is about 16175.3076632255. The cubic root of 261640578 is about 639.5900515935.

The spelling of 261640578 in words is "two hundred sixty-one million, six hundred forty thousand, five hundred seventy-eight".