81006397943 has 4 divisors (see below), whose sum is σ = 83799722040. Its totient is φ = 78213073848.

The previous prime is 81006397909. The next prime is 81006397973. The reversal of 81006397943 is 34979360018.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34979360018 = 2 ⋅17489680009.

It is a cyclic number.

It is not a de Polignac number, because 81006397943 - 2¹⁴ = 81006381559 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81006397891 and 81006397900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81006397973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1396662005 + ... + 1396662062.

It is an arithmetic number, because the mean of its divisors is an integer number (20949930510).

Almost surely, 2^81006397943 is an apocalyptic number.

81006397943 is a deficient number, since it is larger than the sum of its proper divisors (2793324097).

81006397943 is a wasteful number, since it uses less digits than its factorization.

81006397943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2793324096.

The product of its (nonzero) digits is 979776, while the sum is 50.

The spelling of 81006397943 in words is "eighty-one billion, six million, three hundred ninety-seven thousand, nine hundred forty-three".