820609509 has 4 divisors (see below), whose sum is σ = 1094146016. Its totient is φ = 547073004.

The previous prime is 820609507. The next prime is 820609513. The reversal of 820609509 is 905906028.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 820609509 - 2¹ = 820609507 is a prime.

It is a super-2 number, since 2×820609509² = 1346799932522442162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820609507) 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, 136768249 + ... + 136768254.

It is an arithmetic number, because the mean of its divisors is an integer number (273536504).

Almost surely, 2^820609509 is an apocalyptic number.

It is an amenable number.

820609509 is a deficient number, since it is larger than the sum of its proper divisors (273536507).

820609509 is a wasteful number, since it uses less digits than its factorization.

820609509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273536506.

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 820609509 is about 28646.2826384158. The cubic root of 820609509 is about 936.2220131824. Note that the first 3 decimals are identical.

The spelling of 820609509 in words is "eight hundred twenty million, six hundred nine thousand, five hundred nine".