261144555 has 16 divisors (see below), whose sum is σ = 477521664. Its totient is φ = 119380320.

The previous prime is 261144551. The next prime is 261144563. The reversal of 261144555 is 555441162.

It is not a de Polignac number, because 261144555 - 2² = 261144551 is a prime.

It is a super-2 number, since 2×261144555² = 136392957212296050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (261144551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1243441 + ... + 1243650.

It is an arithmetic number, because the mean of its divisors is an integer number (29845104).

Almost surely, 2^261144555 is an apocalyptic number.

261144555 is a deficient number, since it is larger than the sum of its proper divisors (216377109).

261144555 is a wasteful number, since it uses less digits than its factorization.

261144555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2487106.

The product of its digits is 24000, while the sum is 33.

The square root of 261144555 is about 16159.9676670469. The cubic root of 261144555 is about 639.1856137273.

The spelling of 261144555 in words is "two hundred sixty-one million, one hundred forty-four thousand, five hundred fifty-five".