251616121 has 2 divisors, whose sum is σ = 251616122. Its totient is φ = 251616120.

The previous prime is 251616109. The next prime is 251616163. The reversal of 251616121 is 121616152.

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., 250778896 + 837225 = 15836^2 + 915^2 .

It is a cyclic number.

It is not a de Polignac number, because 251616121 - 2⁵ = 251616089 is a prime.

It is not a weakly prime, because it can be changed into another prime (251616191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125808060 + 125808061.

It is an arithmetic number, because the mean of its divisors is an integer number (125808061).

Almost surely, 2^251616121 is an apocalyptic number.

It is an amenable number.

251616121 is a deficient number, since it is larger than the sum of its proper divisors (1).

251616121 is an equidigital number, since it uses as much as digits as its factorization.

251616121 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 251616121 is about 15862.4122062188. The cubic root of 251616121 is about 631.3150669001.

The spelling of 251616121 in words is "two hundred fifty-one million, six hundred sixteen thousand, one hundred twenty-one".