251800121 has 2 divisors, whose sum is σ = 251800122. Its totient is φ = 251800120.

The previous prime is 251800111. The next prime is 251800163. The reversal of 251800121 is 121008152.

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., 227406400 + 24393721 = 15080^2 + 4939^2 .

It is a cyclic number.

It is not a de Polignac number, because 251800121 - 2⁶ = 251800057 is a prime.

It is a super-2 number, since 2×251800121² = 126806601871229282, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 251800093 and 251800102.

It is not a weakly prime, because it can be changed into another prime (251800111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125900060 + 125900061.

It is an arithmetic number, because the mean of its divisors is an integer number (125900061).

Almost surely, 2^251800121 is an apocalyptic number.

It is an amenable number.

251800121 is a deficient number, since it is larger than the sum of its proper divisors (1).

251800121 is an equidigital number, since it uses as much as digits as its factorization.

251800121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 251800121 is about 15868.2110207799. The cubic root of 251800121 is about 631.4689172284.

Adding to 251800121 its reverse (121008152), we get a palindrome (372808273).

The spelling of 251800121 in words is "two hundred fifty-one million, eight hundred thousand, one hundred twenty-one".