261331331 has 2 divisors, whose sum is σ = 261331332. Its totient is φ = 261331330.

The previous prime is 261331309. The next prime is 261331349. The reversal of 261331331 is 133133162.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261331331 is a prime.

It is a super-2 number, since 2×261331331² = 136588129124463122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 261331297 and 261331306.

It is not a weakly prime, because it can be changed into another prime (261331351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130665665 + 130665666.

It is an arithmetic number, because the mean of its divisors is an integer number (130665666).

Almost surely, 2^261331331 is an apocalyptic number.

261331331 is a deficient number, since it is larger than the sum of its proper divisors (1).

261331331 is an equidigital number, since it uses as much as digits as its factorization.

261331331 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 23.

The square root of 261331331 is about 16165.7456060647. The cubic root of 261331331 is about 639.3379636795.

Adding to 261331331 its reverse (133133162), we get a palindrome (394464493).

The spelling of 261331331 in words is "two hundred sixty-one million, three hundred thirty-one thousand, three hundred thirty-one".