261158581 has 2 divisors, whose sum is σ = 261158582. Its totient is φ = 261158580.

The previous prime is 261158567. The next prime is 261158593. The reversal of 261158581 is 185851162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 190026225 + 71132356 = 13785^2 + 8434^2 .

It is a cyclic number.

It is not a de Polignac number, because 261158581 - 2⁵ = 261158549 is a prime.

It is a super-2 number, since 2×261158581² = 136407608859867122, 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 261158581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261158501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130579290 + 130579291.

It is an arithmetic number, because the mean of its divisors is an integer number (130579291).

Almost surely, 2^261158581 is an apocalyptic number.

It is an amenable number.

261158581 is a deficient number, since it is larger than the sum of its proper divisors (1).

261158581 is an equidigital number, since it uses as much as digits as its factorization.

261158581 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19200, while the sum is 37.

The square root of 261158581 is about 16160.4016348604. The cubic root of 261158581 is about 639.1970570151.

The spelling of 261158581 in words is "two hundred sixty-one million, one hundred fifty-eight thousand, five hundred eighty-one".