251609243 has 2 divisors, whose sum is σ = 251609244. Its totient is φ = 251609242.

The previous prime is 251609227. The next prime is 251609261. The reversal of 251609243 is 342906152.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 251609243 - 2⁴ = 251609227 is a prime.

It is a super-2 number, since 2×251609243² = 126614422326066098, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (251609203) 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, 125804621 + 125804622.

It is an arithmetic number, because the mean of its divisors is an integer number (125804622).

Almost surely, 2^251609243 is an apocalyptic number.

251609243 is a deficient number, since it is larger than the sum of its proper divisors (1).

251609243 is an equidigital number, since it uses as much as digits as its factorization.

251609243 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 251609243 is about 15862.1954029069. The cubic root of 251609243 is about 631.3093144539.

The spelling of 251609243 in words is "two hundred fifty-one million, six hundred nine thousand, two hundred forty-three".