261143231 has 4 divisors (see below), whose sum is σ = 270148200. Its totient is φ = 252138264.

The previous prime is 261143221. The next prime is 261143291. The reversal of 261143231 is 132341162.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 132341162 = 2 ⋅66170581.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261143231 is a prime.

It is a super-2 number, since 2×261143231² = 136391574194238722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261143197 and 261143206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261143221) 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, 4502441 + ... + 4502498.

It is an arithmetic number, because the mean of its divisors is an integer number (67537050).

Almost surely, 2^261143231 is an apocalyptic number.

261143231 is a deficient number, since it is larger than the sum of its proper divisors (9004969).

261143231 is an equidigital number, since it uses as much as digits as its factorization.

261143231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9004968.

The product of its digits is 864, while the sum is 23.

The square root of 261143231 is about 16159.9267015664. The cubic root of 261143231 is about 639.1845335042.

Adding to 261143231 its reverse (132341162), we get a palindrome (393484393).

The spelling of 261143231 in words is "two hundred sixty-one million, one hundred forty-three thousand, two hundred thirty-one".