261556405 has 8 divisors (see below), whose sum is σ = 342401184. Its totient is φ = 190222800.

The previous prime is 261556397. The next prime is 261556433. The reversal of 261556405 is 504655162.

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

It is not a de Polignac number, because 261556405 - 2³ = 261556397 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 2377731 + ... + 2377840.

It is an arithmetic number, because the mean of its divisors is an integer number (42800148).

Almost surely, 2^261556405 is an apocalyptic number.

It is an amenable number.

261556405 is a deficient number, since it is larger than the sum of its proper divisors (80844779).

261556405 is a wasteful number, since it uses less digits than its factorization.

261556405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4755587.

The product of its (nonzero) digits is 36000, while the sum is 34.

The square root of 261556405 is about 16172.7055559668. The cubic root of 261556405 is about 639.5214562351.

The spelling of 261556405 in words is "two hundred sixty-one million, five hundred fifty-six thousand, four hundred five".