81866463242 has 8 divisors (see below), whose sum is σ = 124015533732. Its totient is φ = 40527952000.

The previous prime is 81866463233. The next prime is 81866463271. The reversal of 81866463242 is 24236466818.

It can be written as a sum of positive squares in 2 ways, for example, as 81789708121 + 76755121 = 285989^2 + 8761^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 202639559 + ... + 202639962.

Almost surely, 2^81866463242 is an apocalyptic number.

81866463242 is a deficient number, since it is larger than the sum of its proper divisors (42149070490).

81866463242 is a wasteful number, since it uses less digits than its factorization.

81866463242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 405279624.

The product of its digits is 2654208, while the sum is 50.

The spelling of 81866463242 in words is "eighty-one billion, eight hundred sixty-six million, four hundred sixty-three thousand, two hundred forty-two".