81550578281738 has 16 divisors (see below), whose sum is σ = 123277551941376. Its totient is φ = 40458998127600.

The previous prime is 81550578281707. The next prime is 81550578281759. The reversal of 81550578281738 is 83718287505518.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 234115538 + ... + 234463613.

It is an arithmetic number, because the mean of its divisors is an integer number (7704846996336).

Almost surely, 2^{81550578281738} is an apocalyptic number.

81550578281738 is a deficient number, since it is larger than the sum of its proper divisors (41726973659638).

81550578281738 is a wasteful number, since it uses less digits than its factorization.

81550578281738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 468579829.

The product of its (nonzero) digits is 150528000, while the sum is 68.

The spelling of 81550578281738 in words is "eighty-one trillion, five hundred fifty billion, five hundred seventy-eight million, two hundred eighty-one thousand, seven hundred thirty-eight".