249172909 has 2 divisors, whose sum is σ = 249172910. Its totient is φ = 249172908.

The previous prime is 249172907. The next prime is 249172919. The reversal of 249172909 is 909271942.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 224700100 + 24472809 = 14990^2 + 4947^2 .

It is a cyclic number.

It is not a de Polignac number, because 249172909 - 2¹ = 249172907 is a prime.

Together with 249172907, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (249172907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 124586454 + 124586455.

It is an arithmetic number, because the mean of its divisors is an integer number (124586455).

Almost surely, 2^249172909 is an apocalyptic number.

It is an amenable number.

249172909 is a deficient number, since it is larger than the sum of its proper divisors (1).

249172909 is an equidigital number, since it uses as much as digits as its factorization.

249172909 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81648, while the sum is 43.

The square root of 249172909 is about 15785.2117185675. The cubic root of 249172909 is about 629.2650445078.

The spelling of 249172909 in words is "two hundred forty-nine million, one hundred seventy-two thousand, nine hundred nine".