816221992 has 8 divisors (see below), whose sum is σ = 1530416250. Its totient is φ = 408110992.

The previous prime is 816221981. The next prime is 816221993. The reversal of 816221992 is 299122618.

It can be written as a sum of positive squares in only one way, i.e., 668015716 + 148206276 = 25846^2 + 12174^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (816221993) 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 as a sum of consecutive naturals, namely, 51013867 + ... + 51013882.

Almost surely, 2^816221992 is an apocalyptic number.

It is an amenable number.

816221992 is a deficient number, since it is larger than the sum of its proper divisors (714194258).

816221992 is a wasteful number, since it uses less digits than its factorization.

816221992 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102027755 (or 102027751 counting only the distinct ones).

The product of its digits is 31104, while the sum is 40.

The square root of 816221992 is about 28569.5990871416. The cubic root of 816221992 is about 934.5504781510.

The spelling of 816221992 in words is "eight hundred sixteen million, two hundred twenty-one thousand, nine hundred ninety-two".