261531223 has 4 divisors (see below), whose sum is σ = 261600408. Its totient is φ = 261462040.

The previous prime is 261531211. The next prime is 261531299. The reversal of 261531223 is 322135162.

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 261531223 - 2⁵ = 261531191 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 (261531323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28573 + ... + 36598.

It is an arithmetic number, because the mean of its divisors is an integer number (65400102).

Almost surely, 2^261531223 is an apocalyptic number.

261531223 is a deficient number, since it is larger than the sum of its proper divisors (69185).

261531223 is an equidigital number, since it uses as much as digits as its factorization.

261531223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69184.

The product of its digits is 2160, while the sum is 25.

The square root of 261531223 is about 16171.9270032980. The cubic root of 261531223 is about 639.5009317314.

Adding to 261531223 its reverse (322135162), we get a palindrome (583666385).

The spelling of 261531223 in words is "two hundred sixty-one million, five hundred thirty-one thousand, two hundred twenty-three".