820816501869 has 72 divisors (see below), whose sum is σ = 1486099443192. Its totient is φ = 432721336320.

The previous prime is 820816501849. The next prime is 820816501889. The reversal of 820816501869 is 968105618028.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (820816501849) and next prime (820816501889).

It can be written as a sum of positive squares in 4 ways, for example, as 191198056644 + 629618445225 = 437262^2 + 793485^2 .

It is not a de Polignac number, because 820816501869 - 2⁷ = 820816501741 is a prime.

It is a super-2 number, since 2×820816501869² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820816501849) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 10699689 + ... + 10776129.

Almost surely, 2^820816501869 is an apocalyptic number.

It is an amenable number.

820816501869 is a deficient number, since it is larger than the sum of its proper divisors (665282941323).

820816501869 is a wasteful number, since it uses less digits than its factorization.

820816501869 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78347 (or 78337 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 820816501869 in words is "eight hundred twenty billion, eight hundred sixteen million, five hundred one thousand, eight hundred sixty-nine".