249791681 has 2 divisors, whose sum is σ = 249791682. Its totient is φ = 249791680.

The previous prime is 249791677. The next prime is 249791701. The reversal of 249791681 is 186197942.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 228493456 + 21298225 = 15116^2 + 4615^2 .

It is a cyclic number.

It is not a de Polignac number, because 249791681 - 2² = 249791677 is a prime.

It is a super-2 number, since 2×249791681² = 124791767793611522, which contains 22 as substring.

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 (249791621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124895840 + 124895841.

It is an arithmetic number, because the mean of its divisors is an integer number (124895841).

Almost surely, 2^249791681 is an apocalyptic number.

It is an amenable number.

249791681 is a deficient number, since it is larger than the sum of its proper divisors (1).

249791681 is an equidigital number, since it uses as much as digits as its factorization.

249791681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 217728, while the sum is 47.

The square root of 249791681 is about 15804.7993027435. The cubic root of 249791681 is about 629.7854993281.

The spelling of 249791681 in words is "two hundred forty-nine million, seven hundred ninety-one thousand, six hundred eighty-one".