261945555 has 8 divisors (see below), whose sum is σ = 419112912. Its totient is φ = 139704288.

The previous prime is 261945547. The next prime is 261945569. The reversal of 261945555 is 555549162.

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

It is not a de Polignac number, because 261945555 - 2³ = 261945547 is a prime.

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, 8731504 + ... + 8731533.

It is an arithmetic number, because the mean of its divisors is an integer number (52389114).

Almost surely, 2^261945555 is an apocalyptic number.

261945555 is a deficient number, since it is larger than the sum of its proper divisors (157167357).

261945555 is a wasteful number, since it uses less digits than its factorization.

261945555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17463045.

The product of its digits is 270000, while the sum is 42.

The square root of 261945555 is about 16184.7321571906. The cubic root of 261945555 is about 639.8384642775.

The spelling of 261945555 in words is "two hundred sixty-one million, nine hundred forty-five thousand, five hundred fifty-five".