81000008 has 8 divisors (see below), whose sum is σ = 151875030. Its totient is φ = 40500000.

The previous prime is 81000001. The next prime is 81000013. The reversal of 81000008 is 80000018.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 45454564 + 35545444 = 6742^2 + 5962^2 .

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

It is a super-2 number, since 2×81000008² = 13122002592000128, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81000008.

It is not an unprimeable number, because it can be changed into a prime (81000001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5062493 + ... + 5062508.

Almost surely, 2^81000008 is an apocalyptic number.

It is an amenable number.

81000008 is a deficient number, since it is larger than the sum of its proper divisors (70875022).

81000008 is a wasteful number, since it uses less digits than its factorization.

81000008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10125007 (or 10125003 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 81000008 is about 9000.0004444444. Note that the first 3 decimals coincide. The cubic root of 81000008 is about 432.6748853367.

The spelling of 81000008 in words is "eighty-one million, eight", and thus it is an aban number and an uban number.