81985924942 has 4 divisors (see below), whose sum is σ = 122978887416. Its totient is φ = 40992962470.

The previous prime is 81985924897. The next prime is 81985924949. The reversal of 81985924942 is 24942958918.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81985924949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20496481234 + ... + 20496481237.

It is an arithmetic number, because the mean of its divisors is an integer number (30744721854).

Almost surely, 2^81985924942 is an apocalyptic number.

81985924942 is a deficient number, since it is larger than the sum of its proper divisors (40992962474).

81985924942 is a wasteful number, since it uses less digits than its factorization.

81985924942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40992962473.

The product of its digits is 14929920, while the sum is 61.

The spelling of 81985924942 in words is "eighty-one billion, nine hundred eighty-five million, nine hundred twenty-four thousand, nine hundred forty-two".