261222817 has 2 divisors, whose sum is σ = 261222818. Its totient is φ = 261222816.

The previous prime is 261222809. The next prime is 261222823. The reversal of 261222817 is 718222162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 254689681 + 6533136 = 15959^2 + 2556^2 .

It is a cyclic number.

It is not a de Polignac number, because 261222817 - 2³ = 261222809 is a prime.

It is not a weakly prime, because it can be changed into another prime (261222827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130611408 + 130611409.

It is an arithmetic number, because the mean of its divisors is an integer number (130611409).

Almost surely, 2^261222817 is an apocalyptic number.

It is an amenable number.

261222817 is a deficient number, since it is larger than the sum of its proper divisors (1).

261222817 is an equidigital number, since it uses as much as digits as its factorization.

261222817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 31.

The square root of 261222817 is about 16162.3889632690. The cubic root of 261222817 is about 639.2494595261.

Adding to 261222817 its reverse (718222162), we get a palindrome (979444979).

The spelling of 261222817 in words is "two hundred sixty-one million, two hundred twenty-two thousand, eight hundred seventeen".