249895721 has 2 divisors, whose sum is σ = 249895722. Its totient is φ = 249895720.

The previous prime is 249895703. The next prime is 249895727. The reversal of 249895721 is 127598942.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 213160000 + 36735721 = 14600^2 + 6061^2 .

It is a cyclic number.

It is not a de Polignac number, because 249895721 - 2¹⁸ = 249633577 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (249895727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124947860 + 124947861.

It is an arithmetic number, because the mean of its divisors is an integer number (124947861).

Almost surely, 2^249895721 is an apocalyptic number.

It is an amenable number.

249895721 is a deficient number, since it is larger than the sum of its proper divisors (1).

249895721 is an equidigital number, since it uses as much as digits as its factorization.

249895721 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 47.

The square root of 249895721 is about 15808.0903653794. The cubic root of 249895721 is about 629.8729238949.

The spelling of 249895721 in words is "two hundred forty-nine million, eight hundred ninety-five thousand, seven hundred twenty-one".