81243583706 has 4 divisors (see below), whose sum is σ = 121865375562. Its totient is φ = 40621791852.

The previous prime is 81243583697. The next prime is 81243583727. The reversal of 81243583706 is 60738534218.

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., 74155459225 + 7088124481 = 272315^2 + 84191^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20310895925 + ... + 20310895928.

Almost surely, 2^81243583706 is an apocalyptic number.

81243583706 is a deficient number, since it is larger than the sum of its proper divisors (40621791856).

81243583706 is a wasteful number, since it uses less digits than its factorization.

81243583706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40621791855.

The product of its (nonzero) digits is 967680, while the sum is 47.

The spelling of 81243583706 in words is "eighty-one billion, two hundred forty-three million, five hundred eighty-three thousand, seven hundred six".