261318331 has 2 divisors, whose sum is σ = 261318332. Its totient is φ = 261318330.

The previous prime is 261318307. The next prime is 261318347. The reversal of 261318331 is 133813162.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 261318331 - 2¹¹ = 261316283 is a prime.

It is a super-2 number, since 2×261318331² = 136574540233251122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261318331.

It is not a weakly prime, because it can be changed into another prime (261313331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130659165 + 130659166.

It is an arithmetic number, because the mean of its divisors is an integer number (130659166).

Almost surely, 2^261318331 is an apocalyptic number.

261318331 is a deficient number, since it is larger than the sum of its proper divisors (1).

261318331 is an equidigital number, since it uses as much as digits as its factorization.

261318331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 28.

The square root of 261318331 is about 16165.3435163005. The cubic root of 261318331 is about 639.3273621552.

The spelling of 261318331 in words is "two hundred sixty-one million, three hundred eighteen thousand, three hundred thirty-one".