81163208228 has 6 divisors (see below), whose sum is σ = 142035614406. Its totient is φ = 40581604112.

The previous prime is 81163208227. The next prime is 81163208281. The reversal of 81163208228 is 82280236118.

It can be written as a sum of positive squares in only one way, i.e., 57388035364 + 23775172864 = 239558^2 + 154192^2 .

It is a super-4 number, since 4×81163208228⁴ (a number of 45 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (81163208227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10145401025 + ... + 10145401032.

It is an arithmetic number, because the mean of its divisors is an integer number (23672602401).

Almost surely, 2^81163208228 is an apocalyptic number.

It is an amenable number.

81163208228 is a deficient number, since it is larger than the sum of its proper divisors (60872406178).

81163208228 is a wasteful number, since it uses less digits than its factorization.

81163208228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20290802061 (or 20290802059 counting only the distinct ones).

The product of its (nonzero) digits is 73728, while the sum is 41.

The spelling of 81163208228 in words is "eighty-one billion, one hundred sixty-three million, two hundred eight thousand, two hundred twenty-eight".