816821776 has 10 divisors (see below), whose sum is σ = 1582592222. Its totient is φ = 408410880.

The previous prime is 816821773. The next prime is 816821777. The reversal of 816821776 is 677128618.

It can be written as a sum of positive squares in only one way, i.e., 805424400 + 11397376 = 28380^2 + 3376^2 .

It is not an unprimeable number, because it can be changed into a prime (816821773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25525665 + ... + 25525696.

Almost surely, 2^816821776 is an apocalyptic number.

It is an amenable number.

816821776 is a deficient number, since it is larger than the sum of its proper divisors (765770446).

816821776 is a wasteful number, since it uses less digits than its factorization.

816821776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51051369 (or 51051363 counting only the distinct ones).

The product of its digits is 225792, while the sum is 46.

The square root of 816821776 is about 28580.0940516297. The cubic root of 816821776 is about 934.7793338577.

The spelling of 816821776 in words is "eight hundred sixteen million, eight hundred twenty-one thousand, seven hundred seventy-six".