81818442 has 12 divisors (see below), whose sum is σ = 177273330. Its totient is φ = 27272808.

The previous prime is 81818437. The next prime is 81818449. The reversal of 81818442 is 24481818.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 81703521 + 114921 = 9039^2 + 339^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81818397 and 81818406.

It is not an unprimeable number, because it can be changed into a prime (81818449) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2272717 + ... + 2272752.

Almost surely, 2^81818442 is an apocalyptic number.

81818442 is an abundant number, since it is smaller than the sum of its proper divisors (95454888).

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

81818442 is a wasteful number, since it uses less digits than its factorization.

81818442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4545477 (or 4545474 counting only the distinct ones).

The product of its digits is 16384, while the sum is 36.

The square root of 81818442 is about 9045.3547194126. The cubic root of 81818442 is about 434.1272712456.

The spelling of 81818442 in words is "eighty-one million, eight hundred eighteen thousand, four hundred forty-two".