820650609 has 21 divisors (see below), whose sum is σ = 1231573819. Its totient is φ = 546584760.

The previous prime is 820650581. The next prime is 820650637. The reversal of 820650609 is 906056028.

The square root of 820650609 is 28647.

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

It is an interprime number because it is at equal distance from previous prime (820650581) and next prime (820650637).

It can be written as a sum of positive squares in only one way, i.e., 540423009 + 280227600 = 23247^2 + 16740^2 .

It is not a de Polignac number, because 820650609 - 2¹⁷ = 820519537 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (820650659) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 772939 + ... + 773999.

Almost surely, 2^820650609 is an apocalyptic number.

820650609 is the 28647-th square number.

820650609 is the 14324-th centered octagonal number.

It is an amenable number.

820650609 is a deficient number, since it is larger than the sum of its proper divisors (410923210).

820650609 is an frugal number, since it uses more digits than its factorization.

820650609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2140 (or 1064 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 36.

The cubic root of 820650609 is about 936.2376430616.

Multiplying 820650609 by its sum of digits (36), we get a square (29543421924 = 171882²).

The spelling of 820650609 in words is "eight hundred twenty million, six hundred fifty thousand, six hundred nine".