249640817 has 4 divisors (see below), whose sum is σ = 252445860. Its totient is φ = 246835776.

The previous prime is 249640793. The next prime is 249640819. The reversal of 249640817 is 718046942.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 718046942 = 2 ⋅359023471.

It can be written as a sum of positive squares in 2 ways, for example, as 59228416 + 190412401 = 7696^2 + 13799^2 .

It is a cyclic number.

It is not a de Polignac number, because 249640817 - 2⁸ = 249640561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (249640819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1402388 + ... + 1402565.

It is an arithmetic number, because the mean of its divisors is an integer number (63111465).

Almost surely, 2^249640817 is an apocalyptic number.

It is an amenable number.

249640817 is a deficient number, since it is larger than the sum of its proper divisors (2805043).

249640817 is an equidigital number, since it uses as much as digits as its factorization.

249640817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2805042.

The product of its (nonzero) digits is 96768, while the sum is 41.

The square root of 249640817 is about 15800.0258544092. The cubic root of 249640817 is about 629.6586855322.

The spelling of 249640817 in words is "two hundred forty-nine million, six hundred forty thousand, eight hundred seventeen".