261808255 has 4 divisors (see below), whose sum is σ = 314169912. Its totient is φ = 209446600.

The previous prime is 261808249. The next prime is 261808297. The reversal of 261808255 is 552808162.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 261808255 - 2¹⁵ = 261775487 is a prime.

It is a super-2 number, since 2×261808255² = 137087124772290050, which contains 22 as substring.

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 3 ways as a sum of consecutive naturals, for example, 26180821 + ... + 26180830.

It is an arithmetic number, because the mean of its divisors is an integer number (78542478).

Almost surely, 2^261808255 is an apocalyptic number.

261808255 is a deficient number, since it is larger than the sum of its proper divisors (52361657).

261808255 is an equidigital number, since it uses as much as digits as its factorization.

261808255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52361656.

The product of its (nonzero) digits is 38400, while the sum is 37.

The square root of 261808255 is about 16180.4899493186. The cubic root of 261808255 is about 639.7266532886.

The spelling of 261808255 in words is "two hundred sixty-one million, eight hundred eight thousand, two hundred fifty-five".