81994075 has 6 divisors (see below), whose sum is σ = 101672684. Its totient is φ = 65595240.

The previous prime is 81994069. The next prime is 81994097. The reversal of 81994075 is 57049918.

It is a de Polignac number, because none of the positive numbers 2^k-81994075 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 in 5 ways as a sum of consecutive naturals, for example, 1639857 + ... + 1639906.

Almost surely, 2^81994075 is an apocalyptic number.

81994075 is a deficient number, since it is larger than the sum of its proper divisors (19678609).

81994075 is a wasteful number, since it uses less digits than its factorization.

81994075 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3279773 (or 3279768 counting only the distinct ones).

The product of its (nonzero) digits is 90720, while the sum is 43.

The square root of 81994075 is about 9055.0579788315. The cubic root of 81994075 is about 434.4376844822.

The spelling of 81994075 in words is "eighty-one million, nine hundred ninety-four thousand, seventy-five".