81236842 has 4 divisors (see below), whose sum is σ = 121855266. Its totient is φ = 40618420.

The previous prime is 81236839. The next prime is 81236873. The reversal of 81236842 is 24863218.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 80442961 + 793881 = 8969^2 + 891^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81236798 and 81236807.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20309209 + ... + 20309212.

Almost surely, 2^81236842 is an apocalyptic number.

81236842 is a deficient number, since it is larger than the sum of its proper divisors (40618424).

81236842 is a wasteful number, since it uses less digits than its factorization.

81236842 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40618423.

The product of its digits is 18432, while the sum is 34.

The square root of 81236842 is about 9013.1482845896. The cubic root of 81236842 is about 433.0961709484.

The spelling of 81236842 in words is "eighty-one million, two hundred thirty-six thousand, eight hundred forty-two".