820664869 has 2 divisors, whose sum is σ = 820664870. Its totient is φ = 820664868.

The previous prime is 820664861. The next prime is 820664893. The reversal of 820664869 is 968466028.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 413634244 + 407030625 = 20338^2 + 20175^2 .

It is a cyclic number.

It is not a de Polignac number, because 820664869 - 2³ = 820664861 is a prime.

It is a super-2 number, since 2×820664869² = 1346981654421574322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820664861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410332434 + 410332435.

It is an arithmetic number, because the mean of its divisors is an integer number (410332435).

Almost surely, 2^820664869 is an apocalyptic number.

It is an amenable number.

820664869 is a deficient number, since it is larger than the sum of its proper divisors (1).

820664869 is an equidigital number, since it uses as much as digits as its factorization.

820664869 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 995328, while the sum is 49.

The square root of 820664869 is about 28647.2488906003. The cubic root of 820664869 is about 936.2430658612.

The spelling of 820664869 in words is "eight hundred twenty million, six hundred sixty-four thousand, eight hundred sixty-nine".