261503 has 4 divisors (see below), whose sum is σ = 285288. Its totient is φ = 237720.

The previous prime is 261467. The next prime is 261509. The reversal of 261503 is 305162.

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

It is a cyclic number.

It is not a de Polignac number, because 261503 - 2⁶ = 261439 is a prime.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261509) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11876 + ... + 11897.

It is an arithmetic number, because the mean of its divisors is an integer number (71322).

2²⁶¹⁵⁰³ is an apocalyptic number.

261503 is a deficient number, since it is larger than the sum of its proper divisors (23785).

261503 is a wasteful number, since it uses less digits than its factorization.

261503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23784.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 261503 is about 511.3736403062. The cubic root of 261503 is about 63.9477927105.

Adding to 261503 its reverse (305162), we get a palindrome (566665).

The spelling of 261503 in words is "two hundred sixty-one thousand, five hundred three".