261513503 has 4 divisors (see below), whose sum is σ = 270531240. Its totient is φ = 252495768.

The previous prime is 261513491. The next prime is 261513509. The reversal of 261513503 is 305315162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 305315162 = 2 ⋅152657581.

It is a cyclic number.

It is not a de Polignac number, because 261513503 - 2²² = 257319199 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261513509) 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, 4508825 + ... + 4508882.

It is an arithmetic number, because the mean of its divisors is an integer number (67632810).

Almost surely, 2^261513503 is an apocalyptic number.

261513503 is a deficient number, since it is larger than the sum of its proper divisors (9017737).

261513503 is an equidigital number, since it uses as much as digits as its factorization.

261513503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9017736.

The product of its (nonzero) digits is 2700, while the sum is 26.

The square root of 261513503 is about 16171.3791310451. The cubic root of 261513503 is about 639.4864883158.

Adding to 261513503 its reverse (305315162), we get a palindrome (566828665).

The spelling of 261513503 in words is "two hundred sixty-one million, five hundred thirteen thousand, five hundred three".