261216331 has 2 divisors, whose sum is σ = 261216332. Its totient is φ = 261216330.

The previous prime is 261216269. The next prime is 261216349. The reversal of 261216331 is 133612162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261216331 - 2²⁵ = 227661899 is a prime.

It is a super-2 number, since 2×261216331² = 136467943162203122, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261216296 and 261216305.

It is not a weakly prime, because it can be changed into another prime (261216031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130608165 + 130608166.

It is an arithmetic number, because the mean of its divisors is an integer number (130608166).

Almost surely, 2^261216331 is an apocalyptic number.

261216331 is a deficient number, since it is larger than the sum of its proper divisors (1).

261216331 is an equidigital number, since it uses as much as digits as its factorization.

261216331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 25.

The square root of 261216331 is about 16162.1883109930. The cubic root of 261216331 is about 639.2441687602.

Adding to 261216331 its reverse (133612162), we get a palindrome (394828493).

The spelling of 261216331 in words is "two hundred sixty-one million, two hundred sixteen thousand, three hundred thirty-one".