81105994 has 4 divisors (see below), whose sum is σ = 121658994. Its totient is φ = 40552996.

The previous prime is 81105991. The next prime is 81106007. The reversal of 81105994 is 49950118.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 49950118 = 2 ⋅24975059.

It can be written as a sum of positive squares in only one way, i.e., 80730225 + 375769 = 8985^2 + 613^2 .

It is a super-3 number, since 3×81105994³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (81105991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20276497 + ... + 20276500.

Almost surely, 2^81105994 is an apocalyptic number.

81105994 is a deficient number, since it is larger than the sum of its proper divisors (40553000).

81105994 is a wasteful number, since it uses less digits than its factorization.

81105994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40552999.

The product of its (nonzero) digits is 12960, while the sum is 37.

The square root of 81105994 is about 9005.8866304212. The cubic root of 81105994 is about 432.8635169801.

The spelling of 81105994 in words is "eighty-one million, one hundred five thousand, nine hundred ninety-four".