81538147238 has 4 divisors (see below), whose sum is σ = 122307220860. Its totient is φ = 40769073618.

The previous prime is 81538147219. The next prime is 81538147267. The reversal of 81538147238 is 83274183518.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83274183518 = 2 ⋅41637091759.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20384536808 + ... + 20384536811.

It is an arithmetic number, because the mean of its divisors is an integer number (30576805215).

Almost surely, 2^81538147238 is an apocalyptic number.

81538147238 is a deficient number, since it is larger than the sum of its proper divisors (40769073622).

81538147238 is a wasteful number, since it uses less digits than its factorization.

81538147238 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40769073621.

The product of its digits is 1290240, while the sum is 50.

The spelling of 81538147238 in words is "eighty-one billion, five hundred thirty-eight million, one hundred forty-seven thousand, two hundred thirty-eight".