816444509 has 4 divisors (see below), whose sum is σ = 824528220. Its totient is φ = 808360800.

The previous prime is 816444493. The next prime is 816444581. The reversal of 816444509 is 905444618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 634788025 + 181656484 = 25195^2 + 13478^2 .

It is a cyclic number.

It is not a de Polignac number, because 816444509 - 2⁴ = 816444493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816444709) 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, 4041704 + ... + 4041905.

It is an arithmetic number, because the mean of its divisors is an integer number (206132055).

Almost surely, 2^816444509 is an apocalyptic number.

It is an amenable number.

816444509 is a deficient number, since it is larger than the sum of its proper divisors (8083711).

816444509 is a wasteful number, since it uses less digits than its factorization.

816444509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8083710.

The product of its (nonzero) digits is 138240, while the sum is 41.

The square root of 816444509 is about 28573.4931186231. The cubic root of 816444509 is about 934.6353956026.

The spelling of 816444509 in words is "eight hundred sixteen million, four hundred forty-four thousand, five hundred nine".