816821066 has 16 divisors (see below), whose sum is σ = 1299545856. Its totient is φ = 383722176.

The previous prime is 816821063. The next prime is 816821099. The reversal of 816821066 is 660128618.

It is a super-2 number, since 2×816821066² = 1334393307722752712, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (816821063) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 506 + ... + 40421.

It is an arithmetic number, because the mean of its divisors is an integer number (81221616).

Almost surely, 2^816821066 is an apocalyptic number.

816821066 is a deficient number, since it is larger than the sum of its proper divisors (482724790).

816821066 is a wasteful number, since it uses less digits than its factorization.

816821066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41533.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 816821066 is about 28580.0816303943. The cubic root of 816821066 is about 934.7790630139.

The spelling of 816821066 in words is "eight hundred sixteen million, eight hundred twenty-one thousand, sixty-six".