261057221 has 2 divisors, whose sum is σ = 261057222. Its totient is φ = 261057220.

The previous prime is 261057179. The next prime is 261057347. The reversal of 261057221 is 122750162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199120321 + 61936900 = 14111^2 + 7870^2 .

It is a cyclic number.

It is not a de Polignac number, because 261057221 - 2⁶ = 261057157 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261057721) 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, 130528610 + 130528611.

It is an arithmetic number, because the mean of its divisors is an integer number (130528611).

Almost surely, 2^261057221 is an apocalyptic number.

It is an amenable number.

261057221 is a deficient number, since it is larger than the sum of its proper divisors (1).

261057221 is an equidigital number, since it uses as much as digits as its factorization.

261057221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 261057221 is about 16157.2652698407. The cubic root of 261057221 is about 639.1143519691.

The spelling of 261057221 in words is "two hundred sixty-one million, fifty-seven thousand, two hundred twenty-one".