81237018747 has 18 divisors (see below), whose sum is σ = 109757161332. Its totient is φ = 53446797144.

The previous prime is 81237018743. The next prime is 81237018749. The reversal of 81237018747 is 74781073218.

It is not a de Polignac number, because 81237018747 - 2² = 81237018743 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81237018696 and 81237018705.

It is not an unprimeable number, because it can be changed into a prime (81237018743) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 38998968 + ... + 39001050.

It is an arithmetic number, because the mean of its divisors is an integer number (6097620074).

Almost surely, 2^81237018747 is an apocalyptic number.

81237018747 is a deficient number, since it is larger than the sum of its proper divisors (28520142585).

81237018747 is an frugal number, since it uses more digits than its factorization.

81237018747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4327 (or 2165 counting only the distinct ones).

The product of its (nonzero) digits is 526848, while the sum is 48.

Multiplying 81237018747 by its sum of digits (48), we get a square (3899376899856 = 1974684²).

The spelling of 81237018747 in words is "eighty-one billion, two hundred thirty-seven million, eighteen thousand, seven hundred forty-seven".