81999306 has 12 divisors (see below), whose sum is σ = 177665202. Its totient is φ = 27333096.

The previous prime is 81999299. The next prime is 81999317. The reversal of 81999306 is 60399918.

It can be written as a sum of positive squares in only one way, i.e., 81162081 + 837225 = 9009^2 + 915^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2277741 + ... + 2277776.

Almost surely, 2^81999306 is an apocalyptic number.

81999306 is an abundant number, since it is smaller than the sum of its proper divisors (95665896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81999306 is a wasteful number, since it uses less digits than its factorization.

81999306 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4555525 (or 4555522 counting only the distinct ones).

The product of its (nonzero) digits is 104976, while the sum is 45.

The square root of 81999306 is about 9055.3468183168. The cubic root of 81999306 is about 434.4469229351.

The spelling of 81999306 in words is "eighty-one million, nine hundred ninety-nine thousand, three hundred six".