261403 has 4 divisors (see below), whose sum is σ = 263088. Its totient is φ = 259720.

The previous prime is 261389. The next prime is 261407. The reversal of 261403 is 304162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 304162 = 2 ⋅152081.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261403 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 (261407) 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, 583 + ... + 928.

It is an arithmetic number, because the mean of its divisors is an integer number (65772).

2²⁶¹⁴⁰³ is an apocalyptic number.

261403 is a deficient number, since it is larger than the sum of its proper divisors (1685).

261403 is a wasteful number, since it uses less digits than its factorization.

261403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1684.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 261403 is about 511.2758550919. The cubic root of 261403 is about 63.9396403572.

Adding to 261403 its reverse (304162), we get a palindrome (565565).

The spelling of 261403 in words is "two hundred sixty-one thousand, four hundred three".