81437642643 has 24 divisors (see below), whose sum is σ = 126361010880. Its totient is φ = 46517535120.

The previous prime is 81437642641. The next prime is 81437642683. The reversal of 81437642643 is 34624673418.

It is not a de Polignac number, because 81437642643 - 2¹ = 81437642641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81437642592 and 81437642601.

It is not an unprimeable number, because it can be changed into a prime (81437642641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 271708 + ... + 486518.

It is an arithmetic number, because the mean of its divisors is an integer number (5265042120).

Almost surely, 2^81437642643 is an apocalyptic number.

81437642643 is a deficient number, since it is larger than the sum of its proper divisors (44923368237).

81437642643 is a wasteful number, since it uses less digits than its factorization.

81437642643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217407 (or 217400 counting only the distinct ones).

The product of its digits is 2322432, while the sum is 48.

The spelling of 81437642643 in words is "eighty-one billion, four hundred thirty-seven million, six hundred forty-two thousand, six hundred forty-three".