261813 has 8 divisors (see below), whose sum is σ = 351648. Its totient is φ = 173264.

The previous prime is 261799. The next prime is 261823. The reversal of 261813 is 318162.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 261813 - 2⁸ = 261557 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 370 + ... + 812.

It is an arithmetic number, because the mean of its divisors is an integer number (43956).

2²⁶¹⁸¹³ is an apocalyptic number.

It is an amenable number.

261813 is a deficient number, since it is larger than the sum of its proper divisors (89835).

261813 is a wasteful number, since it uses less digits than its factorization.

261813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643.

The product of its digits is 288, while the sum is 21.

The square root of 261813 is about 511.6766557114. The cubic root of 261813 is about 63.9730518057.

Adding to 261813 its reverse (318162), we get a palindrome (579975).

The spelling of 261813 in words is "two hundred sixty-one thousand, eight hundred thirteen".