261644 has 12 divisors (see below), whose sum is σ = 462000. Its totient is φ = 129648.

The previous prime is 261643. The next prime is 261673. The reversal of 261644 is 446162.

It is a happy number.

It is a zygodrome in base 2.

It is not an unprimeable number, because it can be changed into a prime (261641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 377 + ... + 815.

It is an arithmetic number, because the mean of its divisors is an integer number (38500).

2²⁶¹⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

261644 is a deficient number, since it is larger than the sum of its proper divisors (200356).

261644 is a wasteful number, since it uses less digits than its factorization.

261644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 592 (or 590 counting only the distinct ones).

The product of its digits is 1152, while the sum is 23.

The square root of 261644 is about 511.5114856970. The cubic root of 261644 is about 63.9592839983.

The spelling of 261644 in words is "two hundred sixty-one thousand, six hundred forty-four".