261231757 has 2 divisors, whose sum is σ = 261231758. Its totient is φ = 261231756.

The previous prime is 261231697. The next prime is 261231811. The reversal of 261231757 is 757132162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 249197796 + 12033961 = 15786^2 + 3469^2 .

It is a cyclic number.

It is not a de Polignac number, because 261231757 - 2⁷ = 261231629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261231857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130615878 + 130615879.

It is an arithmetic number, because the mean of its divisors is an integer number (130615879).

Almost surely, 2^261231757 is an apocalyptic number.

It is an amenable number.

261231757 is a deficient number, since it is larger than the sum of its proper divisors (1).

261231757 is an equidigital number, since it uses as much as digits as its factorization.

261231757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 34.

The square root of 261231757 is about 16162.6655289281. The cubic root of 261231757 is about 639.2567519276.

The spelling of 261231757 in words is "two hundred sixty-one million, two hundred thirty-one thousand, seven hundred fifty-seven".