261399 has 4 divisors (see below), whose sum is σ = 348536. Its totient is φ = 174264.

The previous prime is 261389. The next prime is 261407. The reversal of 261399 is 993162.

261399 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 261399 - 2⁷ = 261271 is a prime.

It is a D-number.

It is a Duffinian number.

261399 is strictly pandigital in base 7.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 261399.

It is not an unprimeable number, because it can be changed into a prime (261329) 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, 43564 + ... + 43569.

It is an arithmetic number, because the mean of its divisors is an integer number (87134).

2²⁶¹³⁹⁹ is an apocalyptic number.

261399 is a deficient number, since it is larger than the sum of its proper divisors (87137).

261399 is an equidigital number, since it uses as much as digits as its factorization.

261399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87136.

The product of its digits is 2916, while the sum is 30.

The square root of 261399 is about 511.2719432944. The cubic root of 261399 is about 63.9393142198.

The spelling of 261399 in words is "two hundred sixty-one thousand, three hundred ninety-nine".