81378576542 has 4 divisors (see below), whose sum is σ = 122067864816. Its totient is φ = 40689288270.

The previous prime is 81378576529. The next prime is 81378576551. The reversal of 81378576542 is 24567587318.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 24567587318 = 2 ⋅12283793659.

It is a congruent number.

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 as a sum of consecutive naturals, namely, 20344644134 + ... + 20344644137.

It is an arithmetic number, because the mean of its divisors is an integer number (30516966204).

Almost surely, 2^81378576542 is an apocalyptic number.

81378576542 is a deficient number, since it is larger than the sum of its proper divisors (40689288274).

81378576542 is a wasteful number, since it uses less digits than its factorization.

81378576542 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40689288273.

The product of its digits is 11289600, while the sum is 56.

The spelling of 81378576542 in words is "eighty-one billion, three hundred seventy-eight million, five hundred seventy-six thousand, five hundred forty-two".