81437642649 has 24 divisors (see below), whose sum is σ = 132613491360. Its totient is φ = 49356145080.

The previous prime is 81437642641. The next prime is 81437642683. The reversal of 81437642649 is 94624673418.

81437642649 is a `hidden beast` number, since 8 + 1 + 4 + 376 + 4 + 264 + 9 = 666.

It is not a de Polignac number, because 81437642649 - 2³ = 81437642641 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81437642595 and 81437642604.

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, 12460407 + ... + 12466940.

It is an arithmetic number, because the mean of its divisors is an integer number (5525562140).

Almost surely, 2^81437642649 is an apocalyptic number.

It is an amenable number.

81437642649 is a deficient number, since it is larger than the sum of its proper divisors (51175848711).

81437642649 is a wasteful number, since it uses less digits than its factorization.

81437642649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24927378 (or 24927361 counting only the distinct ones).

The product of its digits is 6967296, while the sum is 54.

The spelling of 81437642649 in words is "eighty-one billion, four hundred thirty-seven million, six hundred forty-two thousand, six hundred forty-nine".