261220655 has 4 divisors (see below), whose sum is σ = 313464792. Its totient is φ = 208976520.

The previous prime is 261220627. The next prime is 261220693. The reversal of 261220655 is 556022162.

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

It is not a de Polignac number, because 261220655 - 2¹⁴ = 261204271 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26122061 + ... + 26122070.

It is an arithmetic number, because the mean of its divisors is an integer number (78366198).

Almost surely, 2^261220655 is an apocalyptic number.

261220655 is a deficient number, since it is larger than the sum of its proper divisors (52244137).

261220655 is an equidigital number, since it uses as much as digits as its factorization.

261220655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52244136.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 261220655 is about 16162.3220794538. The cubic root of 261220655 is about 639.2476959472.

The spelling of 261220655 in words is "two hundred sixty-one million, two hundred twenty thousand, six hundred fifty-five".