261553 has 4 divisors (see below), whose sum is σ = 268660. Its totient is φ = 254448.

The previous prime is 261529. The next prime is 261557. The reversal of 261553 is 355162.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 169744 + 91809 = 412^2 + 303^2 .

It is a cyclic number.

It is not a de Polignac number, because 261553 - 2¹³ = 253361 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (261557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3498 + ... + 3571.

It is an arithmetic number, because the mean of its divisors is an integer number (67165).

2²⁶¹⁵⁵³ is an apocalyptic number.

It is an amenable number.

261553 is a deficient number, since it is larger than the sum of its proper divisors (7107).

261553 is an equidigital number, since it uses as much as digits as its factorization.

261553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7106.

The product of its digits is 900, while the sum is 22.

The square root of 261553 is about 511.4225259020. The cubic root of 261553 is about 63.9518681078.

The spelling of 261553 in words is "two hundred sixty-one thousand, five hundred fifty-three".