261277855 has 4 divisors (see below), whose sum is σ = 313533432. Its totient is φ = 209022280.

The previous prime is 261277837. The next prime is 261277909. The reversal of 261277855 is 558772162.

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

It is not a de Polignac number, because 261277855 - 2¹⁵ = 261245087 is a prime.

It is a super-2 number, since 2×261277855² = 136532235026802050, 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, 26127781 + ... + 26127790.

It is an arithmetic number, because the mean of its divisors is an integer number (78383358).

Almost surely, 2^261277855 is an apocalyptic number.

261277855 is a deficient number, since it is larger than the sum of its proper divisors (52255577).

261277855 is an equidigital number, since it uses as much as digits as its factorization.

261277855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52255576.

The product of its digits is 235200, while the sum is 43.

The square root of 261277855 is about 16164.0915303026. The cubic root of 261277855 is about 639.2943516499.

The spelling of 261277855 in words is "two hundred sixty-one million, two hundred seventy-seven thousand, eight hundred fifty-five".