249545209 has 3 divisors (see below), whose sum is σ = 249561007. Its totient is φ = 249529412.

The previous prime is 249545189. The next prime is 249545237. The reversal of 249545209 is 902545942.

The square root of 249545209 is 15797.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 181845225 + 67699984 = 13485^2 + 8228^2 .

It is a de Polignac number, because none of the positive numbers 2^k-249545209 is a prime.

It is a super-2 number, since 2×249545209² = 124545622669707362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (249545249) 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 in 2 ways as a sum of consecutive naturals, for example, 7899 + ... + 23695.

Almost surely, 2^249545209 is an apocalyptic number.

249545209 is the 15797-th square number.

249545209 is the 7899-th centered octagonal number.

It is an amenable number.

249545209 is a deficient number, since it is larger than the sum of its proper divisors (15798).

249545209 is an frugal number, since it uses more digits than its factorization.

249545209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31594 (or 15797 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 40.

The cubic root of 249545209 is about 629.5782925697.

Multiplying 249545209 by its product of nonzero digits (129600), we get a square (32341059086400 = 5686920²).

The spelling of 249545209 in words is "two hundred forty-nine million, five hundred forty-five thousand, two hundred nine".