249981521 has 2 divisors, whose sum is σ = 249981522. Its totient is φ = 249981520.

The previous prime is 249981491. The next prime is 249981553. The reversal of 249981521 is 125189942.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 241367296 + 8614225 = 15536^2 + 2935^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-249981521 is a prime.

It is not a weakly prime, because it can be changed into another prime (249989521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124990760 + 124990761.

It is an arithmetic number, because the mean of its divisors is an integer number (124990761).

Almost surely, 2^249981521 is an apocalyptic number.

It is an amenable number.

249981521 is a deficient number, since it is larger than the sum of its proper divisors (1).

249981521 is an equidigital number, since it uses as much as digits as its factorization.

249981521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 41.

The square root of 249981521 is about 15810.8039327543. The cubic root of 249981521 is about 629.9450031776.

The spelling of 249981521 in words is "two hundred forty-nine million, nine hundred eighty-one thousand, five hundred twenty-one".