81371955649 has 8 divisors (see below), whose sum is σ = 82128539520. Its totient is φ = 80618727600.

The previous prime is 81371955647. The next prime is 81371955683. The reversal of 81371955649 is 94655917318.

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 81371955649 - 2¹ = 81371955647 is a prime.

It is a super-2 number, since 2×81371955649² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81371955593 and 81371955602.

It is not an unprimeable number, because it can be changed into a prime (81371955647) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 790222 + ... + 887239.

It is an arithmetic number, because the mean of its divisors is an integer number (10266067440).

Almost surely, 2^81371955649 is an apocalyptic number.

It is an amenable number.

81371955649 is a deficient number, since it is larger than the sum of its proper divisors (756583871).

81371955649 is a wasteful number, since it uses less digits than its factorization.

81371955649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1677911.

The product of its digits is 8164800, while the sum is 58.

The spelling of 81371955649 in words is "eighty-one billion, three hundred seventy-one million, nine hundred fifty-five thousand, six hundred forty-nine".