250781561 has 2 divisors, whose sum is σ = 250781562. Its totient is φ = 250781560.

The previous prime is 250781549. The next prime is 250781567. The reversal of 250781561 is 165187052.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 158256400 + 92525161 = 12580^2 + 9619^2 .

It is a cyclic number.

It is not a de Polignac number, because 250781561 - 2¹⁸ = 250519417 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (250781567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 125390780 + 125390781.

It is an arithmetic number, because the mean of its divisors is an integer number (125390781).

Almost surely, 2^250781561 is an apocalyptic number.

It is an amenable number.

250781561 is a deficient number, since it is larger than the sum of its proper divisors (1).

250781561 is an equidigital number, since it uses as much as digits as its factorization.

250781561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16800, while the sum is 35.

The square root of 250781561 is about 15836.0841434996. The cubic root of 250781561 is about 630.6163121416.

The spelling of 250781561 in words is "two hundred fifty million, seven hundred eighty-one thousand, five hundred sixty-one".