521661121 has 2 divisors, whose sum is σ = 521661122. Its totient is φ = 521661120.

The previous prime is 521661097. The next prime is 521661157. The reversal of 521661121 is 121166125.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 415344400 + 106316721 = 20380^2 + 10311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-521661121 is a prime.

It is not a weakly prime, because it can be changed into another prime (521661181) 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, 260830560 + 260830561.

It is an arithmetic number, because the mean of its divisors is an integer number (260830561).

Almost surely, 2^521661121 is an apocalyptic number.

It is an amenable number.

521661121 is a deficient number, since it is larger than the sum of its proper divisors (1).

521661121 is an equidigital number, since it uses as much as digits as its factorization.

521661121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 720, while the sum is 25.

The square root of 521661121 is about 22839.9019481258. The cubic root of 521661121 is about 805.0005123256. Note that the first 3 decimals are identical.

The spelling of 521661121 in words is "five hundred twenty-one million, six hundred sixty-one thousand, one hundred twenty-one".