81976449721 has 8 divisors (see below), whose sum is σ = 82190795904. Its totient is φ = 81762265200.

The previous prime is 81976449701. The next prime is 81976449743. The reversal of 81976449721 is 12794467918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81976449721 - 2²⁷ = 81842231993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81976449701) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 1010571 + ... + 1088671.

It is an arithmetic number, because the mean of its divisors is an integer number (10273849488).

Almost surely, 2^81976449721 is an apocalyptic number.

It is an amenable number.

81976449721 is a deficient number, since it is larger than the sum of its proper divisors (214346183).

81976449721 is a wasteful number, since it uses less digits than its factorization.

81976449721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80831.

The product of its digits is 6096384, while the sum is 58.

The spelling of 81976449721 in words is "eighty-one billion, nine hundred seventy-six million, four hundred forty-nine thousand, seven hundred twenty-one".