81994042 has 16 divisors (see below), whose sum is σ = 133224840. Its totient is φ = 37622592.

The previous prime is 81994037. The next prime is 81994061. The reversal of 81994042 is 24049918.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 81920601 + 73441 = 9051^2 + 271^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81993992 and 81994010.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4617 + ... + 13612.

Almost surely, 2^81994042 is an apocalyptic number.

81994042 is a deficient number, since it is larger than the sum of its proper divisors (51230798).

81994042 is a wasteful number, since it uses less digits than its factorization.

81994042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18417.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 81994042 is about 9055.0561566453. The cubic root of 81994042 is about 434.4376261998.

The spelling of 81994042 in words is "eighty-one million, nine hundred ninety-four thousand, forty-two".